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 A241359 #6 Jun 02 2025 10:06:39 %S A241359 7,4,55,128,228,1721,5663,11909,69946,220363,570699,2878602,8802473, %T A241359 26886516,121529632,369658890,1215513262,5099671734,15392472866, %U A241359 53972192998,212784319669,651213834921,2381746719520,8889638737979 %N A241359 Number of 4Xn 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of the elements above it or one plus the sum of the elements diagonally to its northwest or zero plus the sum of the elements antidiagonally to its northeast, modulo 4. %C A241359 Row 4 of A241356 %H A241359 R. H. Hardin, <a href="/A241359/b241359.txt">Table of n, a(n) for n = 1..157</a> %e A241359 Some solutions for n=4 %e A241359 ..3..2..3..3....3..2..3..3....2..3..3..3....2..3..3..2....3..2..3..3 %e A241359 ..3..1..2..3....3..1..2..1....2..1..1..1....2..1..1..1....3..1..1..3 %e A241359 ..2..3..0..2....2..3..3..3....3..2..3..2....3..2..3..3....2..1..0..2 %e A241359 ..3..1..1..2....3..2..0..2....3..1..3..1....3..2..2..1....2..0..0..3 %K A241359 nonn %O A241359 1,1 %A A241359 _R. H. Hardin_, Apr 20 2014