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 A055603 #9 Jul 12 2018 05:38:46
%S A055603 0,1,90,2248,43000,755100,13003620,226262400,4037765760,74481120000,
%T A055603 1425927888000,28389466828800,588245898240000,12685887076262400,
%U A055603 284623499160000000,6639289429893120000,160886197351047168000,4046412223559946240000,105527367894862577664000
%N A055603 Number of n X n binary matrices with no zero rows or columns and with n+2 ones.
%F A055603 Number of m X n binary matrices with no zero rows or columns and with k=0..m*n ones is Sum_{i=0..n} (-1)^i*C(n, i)*a(m, n-i, k) where a(m, n, k)=Sum_{i=0..m} (-1)^i*C(m, i)*C((m-i)*n, k).
%F A055603 a(n) = n*(n-1)*(9*n^4+42*n^3+7*n^2-122*n-120)*n!/576. - _Vladeta Jovovic_, Mar 25 2006
%Y A055603 A diagonal of triangle A104601.
%Y A055603 Cf. A055602.
%K A055603 nonn
%O A055603 1,3
%A A055603 _Vladeta Jovovic_, Jun 01 2000
%E A055603 More terms from _Vaclav Kotesovec_, Jul 12 2018