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 A240323 #6 Jun 02 2025 09:49:00 %S A240323 4,17,116,455,1677,8091,28448,117304,513841,1871262,7963314,32859835, %T A240323 125032724,531287384,2129046798,8380565700,35092450158,139319279619, %U A240323 559869375850,2308650810237,9177286253390,37241010454269,151821739788451 %N A240323 Number of nX3 0..3 arrays with no element equal to zero plus the sum of elements to its left or zero plus the sum of elements above it or one plus the sum of the elements diagonally to its northwest, modulo 4. %C A240323 Column 3 of A240327 %H A240323 R. H. Hardin, <a href="/A240323/b240323.txt">Table of n, a(n) for n = 1..210</a> %e A240323 Some solutions for n=4 %e A240323 ..3..2..3....3..2..2....3..2..2....2..3..3....3..2..3....2..3..2....2..3..3 %e A240323 ..2..1..1....2..1..1....2..3..0....3..1..2....2..1..1....3..1..3....3..0..1 %e A240323 ..3..0..2....3..0..0....3..2..0....3..1..3....3..2..2....3..1..2....2..1..1 %e A240323 ..3..2..0....2..1..2....3..2..0....2..3..2....2..3..0....3..2..2....2..1..0 %K A240323 nonn %O A240323 1,1 %A A240323 _R. H. Hardin_, Apr 03 2014