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 A267976 #4 Jan 23 2016 10:03:25 %S A267976 16,256,4096,62500,929296,13498276,192321424,2695374889,37241280400, %T A267976 508180785424,6858511503376,91659848427225,1214228383808400, %U A267976 15957351268208100,208196756833645584,2698422754887026244 %N A267976 Number of 2Xn 0..3 arrays with every repeated value in every row greater than or equal to, and in every column greater than, the previous repeated value. %C A267976 Row 2 of A267974. %H A267976 R. H. Hardin, <a href="/A267976/b267976.txt">Table of n, a(n) for n = 1..210</a> %F A267976 Empirical: a(n) = 70*a(n-1) -2030*a(n-2) +30793*a(n-3) -246680*a(n-4) +794920*a(n-5) +1553979*a(n-6) -13039450*a(n-7) -13949950*a(n-8) +88507965*a(n-9) +242460400*a(n-10) +242460400*a(n-11) +88507965*a(n-12) -13949950*a(n-13) -13039450*a(n-14) +1553979*a(n-15) +794920*a(n-16) -246680*a(n-17) +30793*a(n-18) -2030*a(n-19) +70*a(n-20) -a(n-21) %e A267976 Some solutions for n=4 %e A267976 ..0..3..3..2....0..3..3..2....0..2..1..0....1..0..3..1....1..0..2..0 %e A267976 ..1..2..0..0....1..0..2..0....3..0..1..3....1..3..1..2....3..2..1..1 %Y A267976 Cf. A267974. %K A267976 nonn %O A267976 1,1 %A A267976 _R. H. Hardin_, Jan 23 2016