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 A181236 #5 Jul 22 2025 08:38:09 %S A181236 2,2,4,2,8,14,2,22,182,140,2,72,3362,49772,4322,2,254,69302,33235358, %T A181236 113400002,434542,2,926,1513514,27896484332,5210265060002, %U A181236 4027811102702,144109562,2,3434,34306274,26012734507190,298289608088472002 %N A181236 T(n,k)=Number of (k*n)Xn binary matrices with all row sums equal and all column sums equal. %C A181236 Table starts %C A181236 ............2...................2....................2..................2 %C A181236 ............4...................8...................22.................72 %C A181236 ...........14.................182.................3362..............69302 %C A181236 ..........140...............49772.............33235358........27896484332 %C A181236 .........4322...........113400002........5210265060002.298289608088472002 %C A181236 .......434542.......4027811102702.90698868503010138802................... %C A181236 ....144109562.1237505791330809002........................................ %C A181236 .165431317452............................................................ %H A181236 R. H. Hardin, <a href="/A181236/b181236.txt">Table of n, a(n) for n=1..41</a> %e A181236 All solutions for 6X2 %e A181236 ..0..0....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1 %e A181236 ..0..0....0..1....0..1....0..1....0..1....1..0....1..0....1..0....1..0....1..0 %e A181236 ..0..0....0..1....1..0....1..0....1..0....0..1....0..1....0..1....1..0....1..0 %e A181236 ..0..0....1..0....0..1....1..0....1..0....0..1....1..0....1..0....0..1....0..1 %e A181236 ..0..0....1..0....1..0....1..0....0..1....1..0....1..0....0..1....1..0....0..1 %e A181236 ..0..0....1..0....1..0....0..1....1..0....1..0....0..1....1..0....0..1....1..0 %e A181236 ... %e A181236 ..0..1....1..0....1..0....1..0....1..0....1..0....1..0....1..0....1..0....1..0 %e A181236 ..1..0....0..1....0..1....0..1....0..1....0..1....0..1....1..0....1..0....1..0 %e A181236 ..1..0....0..1....0..1....0..1....1..0....1..0....1..0....0..1....0..1....0..1 %e A181236 ..1..0....0..1....1..0....1..0....0..1....0..1....1..0....0..1....0..1....1..0 %e A181236 ..0..1....1..0....1..0....0..1....1..0....0..1....0..1....1..0....0..1....0..1 %e A181236 ..0..1....1..0....0..1....1..0....0..1....1..0....0..1....0..1....1..0....0..1 %e A181236 ... %e A181236 ..1..0....1..1 %e A181236 ..1..0....1..1 %e A181236 ..1..0....1..1 %e A181236 ..0..1....1..1 %e A181236 ..0..1....1..1 %e A181236 ..0..1....1..1 %Y A181236 Column 1 is A067209 %Y A181236 Row 2 is twice A112849 %K A181236 nonn,tabl %O A181236 1,1 %A A181236 _R. H. Hardin_ Oct 10 2010