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 A202740 #7 Jul 22 2025 16:48:36 %S A202740 2,102,3032,62398,1375912,27842760,578826040,11600238174,239443637912, %T A202740 4806953288872,98795215188760,1991699775933928,40848655904440568, %U A202740 824853028164662088,16889107635602264212,341245428784872621534 %N A202740 Number of nX6 0..1 arrays with row sums equal and column sums unequal to adjacent columns. %C A202740 Column 6 of A202742 %H A202740 R. H. Hardin, <a href="/A202740/b202740.txt">Table of n, a(n) for n = 1..19</a> %e A202740 Some solutions for n=4 %e A202740 ..0..1..0..0..1..1....1..0..1..0..1..1....1..0..0..0..1..1....0..1..1..0..0..0 %e A202740 ..0..1..0..1..0..1....1..0..1..1..1..0....0..1..1..0..1..0....1..1..0..0..0..0 %e A202740 ..1..0..0..1..1..0....1..0..1..1..1..0....0..0..1..1..1..0....0..1..1..0..0..0 %e A202740 ..1..1..0..0..1..0....1..0..1..1..1..0....1..0..1..0..1..0....1..0..0..0..1..0 %K A202740 nonn %O A202740 1,1 %A A202740 _R. H. Hardin_ Dec 23 2011