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 A269208 #6 Apr 20 2020 19:52:43 %S A269208 0,96,18048,12548544,30541426560,292321215814512,11273191243423937904, %T A269208 1787171501783334054571344,1177416215650225851496983234096, %U A269208 3247635013385894059877839733594599296 %N A269208 Number of n X n 0..3 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling three exactly once. %C A269208 Diagonal of A269214. %e A269208 Some solutions for n=3 %e A269208 ..0..2..3. .3..0..0. .1..3..2. .2..0..0. .0..0..0. .1..2..2. .1..3..1 %e A269208 ..0..2..2. .1..1..1. .2..2..2. .1..0..1. .0..1..3. .3..3..2. .1..3..3 %e A269208 ..3..1..0. .3..3..1. .2..3..3. .0..3..2. .3..1..1. .2..3..2. .1..1..0 %Y A269208 Cf. A269214. %K A269208 nonn %O A269208 1,2 %A A269208 _R. H. Hardin_, Feb 20 2016