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 A227022 #6 Jul 23 2025 05:32:09 %S A227022 12,72,335,1366,4948,16115,47659,129463,326522,771653,1722005,3652726, %T A227022 7406710,14426468,27103102,49288384,87029344,149600861,250930856, %U A227022 411535151,661105246,1041922558,1613307461,2457351181,3686223670 %N A227022 Number of nX3 (0,1,2) arrays of permanents of 2X2 subblocks of some (n+1)X4 binary array with rows and columns of the latter in lexicographically nondecreasing order. %C A227022 Column 3 of A227025 %H A227022 R. H. Hardin, <a href="/A227022/b227022.txt">Table of n, a(n) for n = 1..210</a> %F A227022 Empirical: a(n) = (1/2217600)*n^11 + (1/48384)*n^10 + (19/241920)*n^9 + (199/2800)*n^7 - (4291/11520)*n^6 - (3567/1792)*n^5 + (1336261/24192)*n^4 - (95295341/302400)*n^3 + (851237/1440)*n^2 + (8658337/9240)*n - 3550 for n>6 %e A227022 Some solutions for n=4 %e A227022 ..0..0..0....0..1..0....0..0..2....0..1..1....0..0..1....0..1..2....0..0..1 %e A227022 ..0..0..0....0..0..0....0..0..2....1..1..1....0..1..1....0..2..2....1..2..1 %e A227022 ..0..1..0....1..1..1....0..1..1....0..0..1....1..0..0....1..0..0....2..2..2 %e A227022 ..1..0..0....2..2..0....1..1..1....1..1..0....0..0..0....1..0..0....2..2..2 %K A227022 nonn %O A227022 1,1 %A A227022 _R. H. Hardin_ Jun 27 2013