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 A208632 #9 Jul 22 2025 21:27:08 %S A208632 1,5,32,225,1652,12404,94320,722733,5565560,43005391,333132384, %T A208632 2585476348,20097106512,156418938680,1218807197408,9506457334965, %U A208632 74216779041840,579903491112365,4534776883051800,35488119754971345 %N A208632 Number of n X n 0..1 arrays with new values 0..1 introduced in row major order and no element equal to more than one of its immediate leftward or upward or right-upward antidiagonal neighbors. %C A208632 Diagonal of A208637 %H A208632 R. H. Hardin, <a href="/A208632/b208632.txt">Table of n, a(n) for n = 1..27</a> %e A208632 Some solutions for n=4 %e A208632 ..0..1..1..1....0..0..1..0....0..0..1..0....0..1..1..0....0..1..1..1 %e A208632 ..1..0..0..0....1..0..1..0....1..0..1..1....0..0..1..0....1..0..0..1 %e A208632 ..0..1..1..1....1..0..1..0....0..1..0..1....1..0..1..1....1..1..0..1 %e A208632 ..1..0..0..0....1..0..1..0....0..1..0..0....1..0..0..0....0..1..0..1 %K A208632 nonn %O A208632 1,2 %A A208632 _R. H. Hardin_ Feb 29 2012