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 A221854 #5 Jul 23 2025 02:17:19 %S A221854 1,306,10085,465305,19159028,811781250,34109464173,1436352539452, %T A221854 60446151885851,2544184795092968 %N A221854 Number of 3Xn arrays of occupancy after each element stays put or moves to some horizontal, diagonal or antidiagonal neighbor, without consecutive moves in the same direction. %C A221854 Row 3 of A221852 %e A221854 Some solutions for n=3 %e A221854 ..2..1..1....0..1..0....0..0..1....2..1..0....1..1..3....1..0..0....1..0..2 %e A221854 ..0..0..0....0..3..2....0..4..1....1..0..1....0..0..1....1..3..1....3..0..1 %e A221854 ..3..1..1....0..3..0....0..1..2....1..3..0....0..2..1....2..1..0....0..2..0 %K A221854 nonn %O A221854 1,2 %A A221854 _R. H. Hardin_ Jan 27 2013