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 A184557 #7 Jun 02 2025 03:48:31 %S A184557 336,5736,91157,1486258,24057629,390354307,6329171799,102644935902, %T A184557 1664547601646,26993866274311,437754652218346,7099004652318411, %U A184557 115123459690848087,1866939760799593583,30275877954690891176 %N A184557 Number of (n+1)X3 0..2 arrays with no 2X2 subblock summing to less than 4. %C A184557 Column 2 of A184564 %H A184557 R. H. Hardin, <a href="/A184557/b184557.txt">Table of n, a(n) for n = 1..200</a> %F A184557 Empirical: a(n)=15*a(n-1)+43*a(n-2)-381*a(n-3)-42*a(n-4)+1696*a(n-5)-590*a(n-6)-2216*a(n-7)+1085*a(n-8)+858*a(n-9)-456*a(n-10)-88*a(n-11)+48*a(n-12) %e A184557 Some solutions for 5X3 %e A184557 ..0..0..1....0..0..2....0..1..0....0..0..0....0..1..1....0..1..1....0..0..2 %e A184557 ..2..2..1....2..2..0....2..2..1....2..2..2....2..2..2....2..2..0....2..2..2 %e A184557 ..1..1..2....0..2..0....2..0..2....2..1..1....0..2..0....0..2..0....1..1..1 %e A184557 ..1..1..1....1..2..2....1..1..1....0..2..1....2..1..2....1..2..1....2..2..2 %e A184557 ..1..2..2....1..2..0....2..0..2....2..2..1....2..1..0....2..1..0....2..1..1 %K A184557 nonn %O A184557 1,1 %A A184557 _R. H. Hardin_ Jan 17 2011