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 A267961 #6 Jun 17 2021 14:16:03 %S A267961 9,81,576,3969,25281,155236,915849,5253264,29365561,160731684, %T A267961 863478225,4564353600,23782266225,122339052900,622112365081, %U A267961 3130733894544,15606442349001,77125175024836,378120197667969,1840241149473024 %N A267961 Number of n X 2 0..2 arrays with every repeated value in every row and column greater than the previous repeated value. %C A267961 Column 2 of A267966. %H A267961 R. H. Hardin, <a href="/A267961/b267961.txt">Table of n, a(n) for n = 1..210</a> %F A267961 Empirical: a(n) = 21*a(n-1) -153*a(n-2) +263*a(n-3) +2094*a(n-4) -9792*a(n-5) -2752*a(n-6) +86256*a(n-7) -85536*a(n-8) -338048*a(n-9) +554496*a(n-10) +571392*a(n-11) -1335296*a(n-12) -98304*a(n-13) +1179648*a(n-14) -524288*a(n-15). %e A267961 Some solutions for n=6 %e A267961 ..0..1....0..0....1..2....2..0....0..1....1..2....0..1....1..2....2..2....0..0 %e A267961 ..1..0....1..2....0..1....0..1....1..0....0..1....2..0....0..0....0..0....1..0 %e A267961 ..0..1....0..1....0..1....1..1....2..2....1..2....2..1....1..0....0..0....0..2 %e A267961 ..2..1....2..1....1..2....0..0....1..1....0..0....0..2....2..2....1..1....2..1 %e A267961 ..0..2....0..0....0..2....2..1....0..0....2..2....2..0....1..2....0..2....0..2 %e A267961 ..0..0....1..1....2..1....1..0....2..2....0..0....0..2....0..1....2..0....1..1 %Y A267961 Cf. A267966. %K A267961 nonn %O A267961 1,1 %A A267961 _R. H. Hardin_, Jan 22 2016