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 A251066 #6 Jun 02 2025 10:17:57 %S A251066 336,2740,17129,89429,410718,1716324,6678657,24601591,86829924, %T A251066 296316228,984577369,3202676417,10242533906,32315864964,100861744449, %U A251066 312101151267,959163561400,2931830099988,8923446044937,27069106904461,81899632621478 %N A251066 Number of (2+1)X(n+1) 0..2 arrays with no 2X2 subblock having x11-x00 less than x10-x01. %C A251066 Row 2 of A251065 %H A251066 R. H. Hardin, <a href="/A251066/b251066.txt">Table of n, a(n) for n = 1..210</a> %F A251066 Empirical: a(n) = 18*a(n-1) -146*a(n-2) +706*a(n-3) -2268*a(n-4) +5102*a(n-5) -8246*a(n-6) +9654*a(n-7) -8131*a(n-8) +4808*a(n-9) -1896*a(n-10) +448*a(n-11) -48*a(n-12) %e A251066 Some solutions for n=4 %e A251066 ..2..2..2..1..2....0..0..0..0..0....1..2..2..1..2....0..0..1..1..1 %e A251066 ..0..0..0..1..2....0..0..0..2..2....0..0..1..2..1....1..2..1..2..2 %e A251066 ..0..1..2..1..0....2..2..2..1..1....2..2..1..0..2....1..0..2..1..2 %K A251066 nonn %O A251066 1,1 %A A251066 _R. H. Hardin_, Nov 29 2014