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 A120283 #2 Mar 31 2012 13:20:27
%S A120283 5,1,-5,7,-15,7601,-91,3617,-745739,3317609,-5981591,5436374093,
%T A120283 -213827575,213745149261,-249859397004145,238988952277727,
%U A120283 -28354566442037,26315271553053477373,-108409774812137683,3394075340453838586663
%N A120283 Numerator of the coefficients of the k^2 terms of Sum[Sum[(i+j)^(2n),{i,1,k}],{j,1,k}].
%F A120283 a(n) = numerator[Coefficient[Sum[Sum[(i+j)^(2n),{i,1,k}],{j,1,k}],k,2]]. a(n) = A100615(2n) - bisection of the numerators of B(n)(2).
%t A120283 Numerator[Coefficient[Table[Sum[Sum[(i+j)^(2n),{i,1,k}],{j,1,k}],{n,1,20}],k,2]]
%Y A120283 Cf. A100615, A027643.
%K A120283 frac,sign
%O A120283 1,1
%A A120283 _Alexander Adamchuk_, Jul 06 2006