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 A240268 #6 Jun 02 2025 09:44:58 %S A240268 24,157,919,8265,49921,382690,3076452,19781372,154994425,1144262410, %T A240268 7794166168,60672207307,432430357219,3074960725990,23390892029200, %U A240268 165455143739679,1206985642463001,8980338421458244,63888419650679414 %N A240268 Number of nX4 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of elements above it or one plus the sum of the elements diagonally to its northwest, modulo 4. %C A240268 Column 4 of A240271 %H A240268 R. H. Hardin, <a href="/A240268/b240268.txt">Table of n, a(n) for n = 1..210</a> %e A240268 Some solutions for n=4 %e A240268 ..3..2..2..2....3..2..2..0....3..0..0..0....3..2..3..3....3..2..2..0 %e A240268 ..3..1..1..2....3..2..2..2....2..3..0..2....3..1..1..3....3..1..1..0 %e A240268 ..2..1..2..3....2..3..3..2....3..2..0..0....2..3..2..1....2..3..3..3 %e A240268 ..2..0..3..2....2..1..1..3....2..1..2..0....3..0..2..2....3..0..2..2 %K A240268 nonn %O A240268 1,1 %A A240268 _R. H. Hardin_, Apr 03 2014