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 A240462 #6 Jun 02 2025 09:58:57 %S A240462 12,102,874,7589,65723,568370,4916340,42530527,367908385,3182471383, %T A240462 27528807013,238127592175,2059829147851,17817722472564, %U A240462 154124971684131,1333195242928609,11532260863126369,99755106819505532,862890740313446216 %N A240462 Number of 3Xn 0..3 arrays with no element equal to one plus the sum of elements to its left or three plus the sum of the elements above it or one plus the sum of the elements diagonally to its northwest, modulo 4. %C A240462 Row 3 of A240460 %H A240462 R. H. Hardin, <a href="/A240462/b240462.txt">Table of n, a(n) for n = 1..210</a> %F A240462 Empirical: a(n) = 18*a(n-1) -105*a(n-2) +200*a(n-3) +242*a(n-4) -2119*a(n-5) +7083*a(n-6) -9004*a(n-7) -24192*a(n-8) +72426*a(n-9) -3118*a(n-10) -103236*a(n-11) -4239*a(n-12) +64281*a(n-13) +119026*a(n-14) -161710*a(n-15) +142844*a(n-16) -25892*a(n-17) -337024*a(n-18) +223288*a(n-19) +175280*a(n-20) -145120*a(n-21) -22528*a(n-22) +23040*a(n-23) %e A240462 Some solutions for n=4 %e A240462 ..2..2..0..2....0..0..2..2....2..2..2..2....2..0..2..0....0..2..0..2 %e A240462 ..0..0..0..0....0..2..0..2....0..0..0..2....0..0..0..2....0..3..1..3 %e A240462 ..0..0..2..0....2..2..2..2....3..2..0..1....0..0..0..0....2..2..3..1 %K A240462 nonn %O A240462 1,1 %A A240462 _R. H. Hardin_, Apr 05 2014