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 A297316 #4 Dec 28 2017 07:29:35 %S A297316 1,21,117,497,2577,13937,72541,375054,1951949,10170792,52930039, %T A297316 275412159,1433386475,7460147264,38825258091,202060807970, %U A297316 1051605128451,5472968149750,28483454530439,148239012444720,771493812884305 %N A297316 Number of 3Xn 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 1 or 2 neighboring 1s. %C A297316 Row 3 of A297314. %H A297316 R. H. Hardin, <a href="/A297316/b297316.txt">Table of n, a(n) for n = 1..210</a> %F A297316 Empirical: a(n) = 5*a(n-1) -7*a(n-2) +42*a(n-3) -20*a(n-4) +120*a(n-5) -109*a(n-6) +179*a(n-7) -371*a(n-8) +53*a(n-9) +390*a(n-10) -408*a(n-11) +204*a(n-12) -101*a(n-13) -43*a(n-14) +151*a(n-15) -139*a(n-16) +61*a(n-17) +2*a(n-18) -21*a(n-19) +15*a(n-20) -2*a(n-21) -a(n-22) +a(n-23) %e A297316 Some solutions for n=5 %e A297316 ..0..0..0..1..1. .1..1..1..0..1. .0..0..0..1..1. .0..0..0..1..1 %e A297316 ..0..1..1..0..1. .0..0..0..1..0. .0..1..1..0..1. .0..0..0..1..0 %e A297316 ..0..0..0..1..1. .0..0..0..0..0. .1..0..1..1..0. .0..0..0..1..1 %Y A297316 Cf. A297314. %K A297316 nonn %O A297316 1,2 %A A297316 _R. H. Hardin_, Dec 28 2017