CINXE.COM

<!DOCTYPE html><html lang="en-US"><head><title>Just a moment...</title><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta name="robots" content="noindex,nofollow"><meta name="viewport" content="width=device-width,initial-scale=1"><style>*{box-sizing:border-box;margin:0;padding:0}html{line-height:1.15;-webkit-text-size-adjust:100%;color:#313131;font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol,Noto Color Emoji}body{display:flex;flex-direction:column;height:100vh;min-height:100vh}.main-content{margin:8rem auto;max-width:60rem;padding-left:1.5rem}@media (width <= 720px){.main-content{margin-top:4rem}}.h2{font-size:1.5rem;font-weight:500;line-height:2.25rem}@media (width <= 720px){.h2{font-size:1.25rem;line-height:1.5rem}}#challenge-error-text{background-image:url(data:image/svg+xml;base64,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);background-repeat:no-repeat;background-size:contain;padding-left:34px}@media (prefers-color-scheme:dark){body{background-color:#222;color:#d9d9d9}}</style><meta http-equiv="refresh" content="390"></head><body class="no-js"><div class="main-wrapper" role="main"><div class="main-content"><noscript><div class="h2"><span id="challenge-error-text">Enable JavaScript and cookies to continue</span></div></noscript></div></div><script>(function(){window._cf_chl_opt={cvId: '3',cZone: "oeis.org",cType: 'managed',cRay: '92e13f6af8e3404e',cH: '2hJnZ8_9vtPKeGyEo2moZPKToEJGHCMZEWmLb5GDlGU-1744277659-1.2.1.1-c8rERx_7OIK9DZrKkUI9Uu2LqoIL3kkrfNRdYCyyUT_XxdJs8ujOOSJkuNHj_Xki',cUPMDTk: "\/?language=chineseS&__cf_chl_tk=RPvAAF2oWGjGpeFauXCYu53qSgqb68ayHU9UCS4hj.0-1744277659-1.0.1.1-Ej5raNEYGdr.hkRQH7idGt9Ad5UXJPfTQwzV81Dewow",cFPWv: 'b',cITimeS: '1744277659',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported_browser_beacon",fa: "\/?language=chineseS&__cf_chl_f_tk=RPvAAF2oWGjGpeFauXCYu53qSgqb68ayHU9UCS4hj.0-1744277659-1.0.1.1-Ej5raNEYGdr.hkRQH7idGt9Ad5UXJPfTQwzV81Dewow",md: "65edrTKqO0U5uifvnx4mpgvnMl1VzDHMMT0zXeGrMqs-1744277659-1.2.1.1-tOP_SB9FYiCRAWG02zRX9EdtbiwgpNnoifBiKTrD5ml_XUipew6LCgCwdTa9MEXflAm5sQcOyWqPdYNSvMWOw73eABYn84IzfZ7w4zpH2XVp8PkOamkkjjPwlaFoUhhYFEYFXZukyQF6C1xme13WDVr062c0KoWswjt_St0Z8NAEV4xWZkN1qEb7_zKI5qZVSrcLkLjiyTd4ZgSRFpylWXH_adXcYxXaOt9z5Ot56odSTuhj7B_E01PJkGyF_k.Bjg_9tTquhyCPROfb46THpm.K.YqlJs_ib5JflvoU2jn_BfW9P4AnWOxjcitf16Z4K2ke9MR1f8QGuA8bupRKAb2kIH7AHrIRkIIe5iJVD3gEo_QCuzpe89zlak9GFXQor0LVncnbjoNQz6j55ZVFMGmYulVyT0JDU5BBspVZQsFxqZ3fS4XCp_Lj.4Pe22CiUQZ1Pwgjl8GAqEYTHz8Hc5HA2H2oxQqRuFag5ZVd3GoAC8lYhU8ogUiiiJYrZEz0agvMl7IZrSTmOcerqySSIA47c8jwTAGYOZX148JbeEuUa88lqHPoKsnIkCfkthjvR.LqXGQ5tCMNa.LbHMIUI9ZxpMRhPsEPAPI3Lg3KId_RpEZ3PFKk_PUsky2wabwAanmNOar2p..sEY_gk2_MOPlN..rJpeHvRh2SaCK.1FdFmiw44DI0VFrN_fUGF4s0sxupoyCLHLMdCsctwSfBelTuHNTh1aooT5rWPCS00gWks4KZqdfH344567Rz5ZFmnlYBhayLtM5wSmaQzjdEWJ8i8O5SFAWBpsvBAxPYzid.rOiW9VF4VmYxZInGR2RroxyHFqMtOY7xyKySjZhbHSNn9hL78fOT1rqsVmkp6LDNAZORV7nZ4LLcz6WobVNGpXfoRzrU7ulm6Yv4K_yySCvN3QdNtdSnmUCAET0Ygl1WTP4hbP8vtnRViAXRaD.XA7TEaSG5uGRYGip9kxr_W_UXnqOUxsd8cmwc48k.H__lQwwJDBxBuZaq0qg4EDg7DE54bnPzf59MDKqPOOPUmUegkhbHuelbudt9nCTuhVcnXIAqX5BqmwA2KI4xYGHAhteKvddcsVhF9rnq35SqYOE_zdyqX0A04g3jFQ6OZik",mdrd: "f8ntuvMAjdWDawkut9nP1K2as60sAJ8rSU52U7gHeE4-1744277659-1.2.1.1-3qIAy2ciNlPQ6YXVL0gkAbK5feeZd.1mXW0AAAN_PYPAOU4Jz2KjEVTboJ.Q7whZ0YF5Iqy3p3VooirlB7gXH9DJJcUgV_fqwHx9kSFexQH0pbc9AOKOqvhqKn4VODtbyMQMQbFbJ6ZbWjemF4c5WA1cyE7UCCdzcXIeTAbBUjOkdGktdFkzXCm8QB0wrLc7jjjDthDo2OFda6QtBlqJ_cLbZ5saM1GeOX6QXT_nL08QKvG9esP72UpH7CbVf76rxgFbwvRy.F2wzHKSJ1v1dR20MfgQG0nU80J_oSBHZCp2d3sdvTl8lXHIoeiNnUN6KV85YC0gIHiVh5sUgb6Nq468Z.dMAbqO91bYkyJ3g8u0mCV9G3TmcJUkc_q.ZTQhp1tqnMzt8JPCIGVlh8wYthxSUmkBI9y4SVMdfVFn6PasM5N89yMTDNcTfadyX55MA4jTZ90Udjf1lrYvTZ_DK6G_4jIlhBn702zSLazTbdYfGPEDa7I1GPBHxCf6iNfdk1DqZKPuSDS_vUa0XfAunq7NZyRupKziA5uAgF9NDRa6GFbWMcy0.WcXTQuVIyveptHfYlJr2.hffIjLmmxLin3QDqB0BDCVqOCm1NAuhfYVQ7WO1kT4OYnIkBx5PEGouqszCcKgNx69bO7N6u38JgJ5vO06XzhMqIeGWSRG5JoyuPGjyiAV2PYP.fIV4Eoo2.x6NoUShwKa0Q.y4Y19qtx83n_WntN7RyI3vsCvIyyIUdMP16D5VMQrpvVuHsK_Z3nwFKKLgpBUpwUXpwJ0z.BWEYsMGCrCvM2ieVvnjwRVBoVxaN4.Tt5TEA6SoRqWqu8XQOn3pzM3fH1apfH3.8oPpeiRU4XMnYalARBYDQxavWgY0.HwE.trHg7e3IryyI3D28dpSEtAEFCVOgUDI271I.UIufOQbkCudnoXiJZjgRq4o.mZMbdxzCis896eJd_aR88qSs1cauxXCoDlubAk6pK84kMXNuUAj8_gOdjy2ZgS0_lmmk5Rl8QzsCDGMHDD4r3giyghAb09zbjRsAyyQfhNcyXnb7xA8qa1sc22nyL6EWgp4WP9MuBDzMbmEKhfMvrWm8NQHYS51KuBTZ8GmsDfxarI_zSmtXQj6z1_mXmFo0vYJvkCQwXTfr11xaKBhZISJYwBRRIAMoS_OnAQz.GwoVblorhk9ouDfHC4IejV0PyGSxt118RRvE9tTIlEklITSHGOd4TGH1O3fZufKmSE5_PuKeGhW5dIL8eiDeAF0_fh_fTnDfb..zqAlnkNEoq88TwzMYpVS61LP4V9bVp0HwoXeSJM48vNxLoaHG7c00t3CRg4A8SGOxVHuSdAZuk8oEtKgDjWhMHvNQ6.oQmHcZnLV30.lzQzAfk5izSO5b1KAg4W50Yiq3NFo9eEIuUPgANM84_FJNuNu7U3PNvu07iHnRWPBMsgEVxJdGOhGAVe7qmUdFIqzAaJWZ8Kw8d5d7NE0ak7Hzlt43Z6Ryi8Sd0520evVNWfrSjeDJ6AR0BmucWIIUcSxopibZUf.WowhFQhdfqB1RZ4NGvJFTIqlM.aX9RgOYLg9Pygk3fq5WlpgSck9yV1vd5HfnRXl79CDVeVpf7SCsix0qTb1ZA54Zle2uFN2ZUwz5Q7wXflKc6R1g7OcShHmPjEShJXlzAhRr9PyJx3rW5BRzCHD92sh_kifMHN5PLZwq7yIWis0b0UAlDzxU7WWgNfJS5op7gwPze5v4m_acADj7CYs2O0lLdhqNHYmjkBcWERkFvAuMgBz7o0wqDNQ0FGq1YUz75rGBHbCMIgEpnaLP54nQmf6ihHDna4SWRgzw6xBsEQX68rzy17jQBQiCw0HxUCbcD31PNBBE7smD5doerjKOwYw.hI5xKActmnoLj9c97X.wWCbR8d6GYui7z88kZAn4UMYXazAZMeK1mbOp3Lg8BS45MnIqCEo3uTuaC.6jE_Xdcm.9G2_0t.tSk9Eq2M85gquqKJSa9oIoEk2CYgMLtNOeM81XG6uI.FKztWD4_oH8NaZdHCMg.zDKhL"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=92e13f6af8e3404e';window._cf_chl_opt.cOgUHash = location.hash === '' && location.href.indexOf('#') !== -1 ? '#' : location.hash;window._cf_chl_opt.cOgUQuery = location.search === '' && location.href.slice(0, location.href.length - window._cf_chl_opt.cOgUHash.length).indexOf('?') !== -1 ? '?' : location.search;if (window.history && window.history.replaceState) {var ogU = location.pathname + window._cf_chl_opt.cOgUQuery + window._cf_chl_opt.cOgUHash;history.replaceState(null, null, "\/?language=chineseS&__cf_chl_rt_tk=RPvAAF2oWGjGpeFauXCYu53qSgqb68ayHU9UCS4hj.0-1744277659-1.0.1.1-Ej5raNEYGdr.hkRQH7idGt9Ad5UXJPfTQwzV81Dewow" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>