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 A215955 #6 Apr 17 2022 20:54:19 %S A215955 1,4,29,313,6150,145563,5219070,208181894,11412814314,670592486703, %T A215955 51088102234508,4085932956830052,407520605922011467, %U A215955 42123055901071684382,5279748839226156263229,679936583636831702045901 %N A215955 Number of horizontal, vertical and diagonal neighbor colorings of the even squares of an n X 4 array with new integer colors introduced in row major order. %C A215955 Column 4 of A215959. %H A215955 R. H. Hardin, <a href="/A215955/b215955.txt">Table of n, a(n) for n = 1..20</a> %e A215955 Some solutions for n=4 %e A215955 ..0..x..1..x....0..x..1..x....0..x..1..x....0..x..1..x....0..x..1..x %e A215955 ..x..2..x..3....x..1..x..0....x..1..x..2....x..2..x..3....x..2..x..3 %e A215955 ..4..x..0..x....2..x..3..x....3..x..4..x....2..x..4..x....2..x..0..x %e A215955 ..x..1..x..2....x..4..x..2....x..5..x..1....x..3..x..5....x..0..x..2 %Y A215955 Cf. A215959. %K A215955 nonn %O A215955 1,2 %A A215955 _R. H. Hardin_, Aug 28 2012