This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A034415 #22 Jul 08 2025 20:22:09 %S A034415 1,2576,535095,18106704,369844880,6101289120,90184804281, %T A034415 1251098739072,16681003659936,216644275600560,2763033644875595, %U A034415 34784314216176096,433742858109499536,5369839142579042560 %N A034415 Second term in extremal weight enumerator of doubly-even binary self-dual code of length 24n. %C A034415 The terms become negative at n=154 and so certainly by that point the extremal codes do not exist (see references). %C A034415 Up to n = 250 the terms steadily increase in magnitude, but their sign changes from positive to negative at n = 154. %D A034415 F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier-North Holland, 1978, see Theorem 13, p. 624. %H A034415 N. J. A. Sloane, <a href="/A034415/b034415.txt">Table of n, a(n) for n = 0..250</a> %H A034415 C. L. Mallows and N. J. A. Sloane, <a href="http://dx.doi.org/10.1016/S0019-9958(73)90273-8">An Upper Bound for Self-Dual Codes</a>, Information and Control, 22 (1973), 188-200. %H A034415 G. Nebe, E. M. Rains and N. J. A. Sloane, <a href="http://neilsloane.com/doc/cliff2.html">Self-Dual Codes and Invariant Theory</a>, Springer, Berlin, 2006. %H A034415 E. M. Rains and N. J. A. Sloane, Self-dual codes, pp. 177-294 of Handbook of Coding Theory, Elsevier, 1998 (<a href="http://neilsloane.com/doc/self.txt">Abstract</a>, <a href="http://neilsloane.com/doc/self.pdf">pdf</a>, <a href="http://neilsloane.com/doc/self.ps">ps</a>). %H A034415 N. J. A. Sloane, <a href="http://neilsloane.com/doc/sg.txt">My favorite integer sequences</a>, in Sequences and their Applications (Proceedings of SETA '98). %e A034415 At length 24, the weight enumerator (of the Golay code) is 1+759*x^8+2576*x^12+..., with leading coefficient 759 and second term 2576. %p A034415 For Maple program see A034414. %Y A034415 Cf. A034414 (leading coefficient), A001380, A034597, A034598. %K A034415 sign %O A034415 0,2 %A A034415 _N. J. A. Sloane_