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A018846 - OEIS
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <html> <head> <link rel="stylesheet" href="/styles.css"> <meta name="format-detection" content="telephone=no"> <meta http-equiv="content-type" content="text/html; charset=utf-8"> <meta name=viewport content="width=device-width, initial-scale=1"> <meta name="keywords" content="OEIS,integer sequences,Sloane" /> <title>A018846 - OEIS</title> <link rel="search" type="application/opensearchdescription+xml" title="OEIS" href="/oeis.xml"> <script> var myURL = "\/A018846\/internal" function redir() { var host = document.location.hostname; if(host != "oeis.org" && host != "127.0.0.1" && !/^([0-9.]+)$/.test(host) && host != "localhost" && host != "localhost.localdomain") { document.location = "https"+":"+"//"+"oeis"+".org/" + myURL; } } function sf() { if(document.location.pathname == "/" && document.f) document.f.q.focus(); } </script> </head> <body bgcolor=#ffffff onload="redir();sf()"> <div class=loginbar> <div class=login> <a href="/login?redirect=%2fA018846%2finternal">login</a> </div> </div> <div class=center><div class=top> <center> <div class=donors> The OEIS is supported by <a href="http://oeisf.org/#DONATE">the many generous donors to the OEIS Foundation</a>. </div> <div class=banner> <a href="/"><img class=banner border="0" width="600" src="/banner2021.jpg" alt="A018846 - OEIS"></a> </div> </center> </div></div> <div class=center><div class=pagebody> <div class=searchbarcenter> <form name=f action="/search" method="GET"> <div class=searchbargreet> <div class=searchbar> <div class=searchq> <input class=searchbox maxLength=1024 name=q value="" title="Search Query"> </div> <div class=searchsubmit> <input type=submit value="Search" name=go> </div> <div class=hints> <span class=hints><a href="/hints.html">Hints</a></span> </div> </div> <div class=searchgreet> (Greetings from <a href="/welcome">The On-Line Encyclopedia of Integer Sequences</a>!) </div> </div> </form> </div> <div class=sequence> <div class=space1></div> <div class=line></div> <div class=seqhead> <div class=seqnumname> <div class=seqnum> <a href="/A018846">A018846</a> </div> <div class=seqname> Strobogrammatic numbers: numbers that are the same upside down (using calculator-style numerals). </div> </div> <div class=scorerefs> 9 </div> </div> <div> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%I #21 Jul 09 2022 11:06:13 </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%S 0,1,2,5,8,11,22,55,69,88,96,101,111,121,151,181,202,212,222,252,282, </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%T 505,515,525,555,585,609,619,629,659,689,808,818,828,858,888,906,916, </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%U 926,956,986,1001,1111,1221,1551,1691,1881,1961,2002,2112,2222,2552,2692,2882 </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%N Strobogrammatic numbers: numbers that are the same upside down (using calculator-style numerals). </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%C A018847 lists primes in this sequence. - _M. F. Hasler_, May 05 2012 </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%H Michael S. Branicky, <a href="/A018846/b018846.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from T. D. Noe) </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o (PARI) is_A018846(n,t=Vec("012..59.86"))={ apply(x->t[eval(x)+1], n=Vec(Str(n)))==vecextract(n, "-1..1") } \\ _M. F. Hasler_, May 05 2012 </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o (Python) </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o from itertools import count, islice, product </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o def ud(s): return s[::-1].translate({ord('6'):ord('9'), ord('9'):ord('6')}) </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o def A018846gen(): # generator of terms </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o yield from [0, 1, 2, 5, 8] </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o for d in count(2): </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o for first in "125689": </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o for rest in product("0125689", repeat=d//2-1): </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o left = first + "".join(rest) </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o for mid in [[""], ["0", "1", "2", "5", "8"]][d%2]: </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o yield int(left + mid + ud(left)) </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%o print(list(islice(A018846gen(), 54))) # _Michael S. Branicky_, Jul 09 2022 </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%Y Cf. A053701 (vertically symmetric numbers), A048708. </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%K nonn,base,easy,nice </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%O 1,3 </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt>%A _David W. Wilson_ </tt></p> <p style="text-indent: -2em; margin-left: 2em; margin-top: 0; margin-bottom: 0;"><tt></tt></p> </div> <div class=space10></div> </div> </div></div> <p> <div class=footerpad></div> <div class=footer> <center> <div class=bottom> <div class=linksbar> <a href="/">Lookup</a> <a href="/wiki/Welcome"><font color="red">Welcome</font></a> <a href="/wiki/Main_Page"><font color="red">Wiki</font></a> <a href="/wiki/Special:RequestAccount">Register</a> <a href="/play.html">Music</a> <a href="/plot2.html">Plot 2</a> <a href="/demo1.html">Demos</a> <a href="/wiki/Index_to_OEIS">Index</a> <a href="/webcam">WebCam</a> <a href="/Submit.html">Contribute</a> <a href="/eishelp2.html">Format</a> <a href="/wiki/Style_Sheet">Style Sheet</a> <a href="/transforms.html">Transforms</a> <a href="/ol.html">Superseeker</a> <a href="/recent">Recents</a> </div> <div class=linksbar> <a href="/community.html">The OEIS Community</a> </div> <div class=linksbar> Maintained by <a href="http://oeisf.org">The OEIS Foundation Inc.</a> </div> <div class=dbinfo>Last modified April 10 16:39 EDT 2025. 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