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 A181231 #7 Jul 22 2025 08:37:40 %S A181231 2,24,1608,483840,595506240,2881362718080,53971723989630720, %T A181231 3905883638351009925120,1097181147335459123569766400, %U A181231 1204583321001156830831556548812800,5203385513364984367494095906614850764800,88913167483454945080054825759528983277687603200 %N A181231 Number of nX(n+1) binary matrices with all rows unique and all columns unique. %F A181231 a(n) = A181230(n,n+1). %Y A181231 Subdiagonal of A181230. %Y A181231 Cf. A088310, A181232, A181233. %K A181231 nonn %O A181231 1,1 %A A181231 _R. H. Hardin_ Oct 10 2010 %E A181231 More terms from _Max Alekseyev_, Jun 18 2016