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 A321969 #18 Dec 04 2018 04:13:24 %S A321969 1,1,1,2,2,3,4,6,8,15,22,45,79,159,312,696,1264,3504 %N A321969 Distinct weight enumerators for binary self-dual codes of length 2n. %C A321969 All binary self-dual codes must have even length. This is due to the fact that all binary self-dual codes contain the "all 1's codeword". If a binary self-dual code could have odd length, the dot product of the "all 1's codeword" with itself would be equal to 1. A dot product of 1 would imply it is not orthogonal to itself and so the code could not be self-dual. %H A321969 W. Cary Huffman and Vera Pless, <a href="https://doi.org/10.1017/CBO9780511807077">Fundamentals of Error Correcting Codes</a>, Cambridge University Press, 2003, Pages 7,252-282,338-393. %e A321969 For n=1 there is only a(1) = 1 distinct weight enumerator for the length 2 binary self-dual codes. Up to permutation equivalence there is only 1 length 2 binary self-dual code. %e A321969 For n=18 there are a(18)=3504 distinct weight enumerators. There are 519492 binary self-dual codes of length 36. However there are only 3504 distinct weight enumerators among the 519492 binary self-dual codes. %Y A321969 Cf. A003179. %K A321969 nonn,more %O A321969 1,4 %A A321969 _Nathan J. Russell_, Nov 22 2018