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 A298921 #4 Jan 29 2018 07:57:47 %S A298921 0,32,3,7,9,12,17,41,42,67,109,172,277,461,722,1167,1889,3052,4937, %T A298921 8001,12922,20907,33829,54732,88557,143301,231842,375127,606969, %U A298921 982092,1589057,2571161,4160202,6731347,10891549,17622892,28514437,46137341 %N A298921 Number of nX5 0..1 arrays with every element equal to 1, 3, 5, 7 or 8 king-move adjacent elements, with upper left element zero. %C A298921 Column 5 of A298924. %H A298921 R. H. Hardin, <a href="/A298921/b298921.txt">Table of n, a(n) for n = 1..210</a> %F A298921 Empirical: a(n) = a(n-1) +a(n-2) +a(n-6) -a(n-7) -a(n-8) for n>11 %e A298921 Some solutions for n=5 %e A298921 ..0..1..0..0..0. .0..0..0..1..0. .0..0..0..0..0. .0..0..1..1..1 %e A298921 ..0..1..0..0..0. .0..0..0..1..0. .0..0..0..0..0. .0..0..1..1..1 %e A298921 ..1..1..0..0..0. .0..0..0..1..1. .1..1..1..1..1. .0..0..1..1..1 %e A298921 ..0..1..0..0..0. .0..0..0..1..0. .1..1..1..1..1. .0..0..1..1..1 %e A298921 ..0..1..0..0..0. .0..0..0..1..0. .1..1..1..1..1. .0..0..1..1..1 %Y A298921 Cf. A298924. %K A298921 nonn %O A298921 1,2 %A A298921 _R. H. Hardin_, Jan 29 2018