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 A184139 #7 Jul 22 2025 09:28:21 %S A184139 5,25,130,650,2942,11819,42305,136564,402910,1099694,2805530,6748066, %T A184139 15412437,33626131,70430778,142218719,277853339,526833235,972034814, %U A184139 1749218190,3076360192,5297051455,8943742419,14828643610,24172697276 %N A184139 Number of nX4 binary arrays with rows and columns in nondecreasing order. %C A184139 Column 4 of A180985 %H A184139 R. H. Hardin, <a href="/A184139/b184139.txt">Table of n, a(n) for n = 1..200</a> %F A184139 Empirical: a(n)=16*a(n-1)-120*a(n-2)+560*a(n-3)-1820*a(n-4)+4368*a(n-5)-8008*a(n-6)+11440*a(n-7)-12870*a(n-8)+11440*a(n-9)-8008*a(n-10)+4368*a(n-11)-1820*a(n-12)+560*a(n-13)-120*a(n-14)+16*a(n-15)-a(n-16) (=polynomial degree 15) %e A184139 Some solutions for 3X4 %e A184139 ..0..0..1..1....0..0..0..0....0..1..1..1....0..0..1..1....0..0..0..1 %e A184139 ..1..1..0..0....0..0..1..1....1..0..0..1....0..1..0..1....0..0..0..1 %e A184139 ..1..1..1..1....1..1..1..1....1..0..1..1....1..1..1..0....0..0..0..1 %K A184139 nonn %O A184139 1,1 %A A184139 _R. H. Hardin_ Jan 09 2011