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 A297539 #4 Dec 31 2017 15:00:07 %S A297539 1,11,35,88,461,2050,8057,35640,158090,679629,2963173,12981912, %T A297539 56560118,246687460,1077347659,4701310128,20514731834,89541862920, %U A297539 390793087220,1705499848917,7443466123759,32485974265409,141779148752373 %N A297539 Number of nX3 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 2 or 3 neighboring 1s. %C A297539 Column 3 of A297544. %H A297539 R. H. Hardin, <a href="/A297539/b297539.txt">Table of n, a(n) for n = 1..210</a> %F A297539 Empirical: a(n) = 3*a(n-1) +38*a(n-3) -40*a(n-4) +7*a(n-5) -296*a(n-6) +98*a(n-7) +36*a(n-8) +388*a(n-9) -96*a(n-10) -104*a(n-11) +400*a(n-12) -192*a(n-13) +128*a(n-14) %e A297539 Some solutions for n=5 %e A297539 ..1..1..0. .0..0..0. .1..1..1. .1..1..0. .0..1..0. .0..1..1. .1..1..0 %e A297539 ..0..1..1. .1..1..0. .0..1..1. .1..1..0. .1..0..1. .0..1..1. .1..1..0 %e A297539 ..1..0..0. .1..1..0. .0..1..0. .0..0..0. .0..1..0. .0..1..1. .0..1..0 %e A297539 ..1..1..1. .1..1..0. .1..1..0. .1..1..0. .0..1..1. .0..1..1. .1..0..1 %e A297539 ..0..1..0. .0..1..1. .1..1..1. .1..1..0. .1..1..0. .0..1..1. .0..1..0 %Y A297539 Cf. A297544. %K A297539 nonn %O A297539 1,2 %A A297539 _R. H. Hardin_, Dec 31 2017