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 A227023 #6 Jul 23 2025 05:32:16 %S A227023 18,171,1366,10050,65317,375270,1924848,8908719,37616613,146387460, %T A227023 529743352,1796459014,5746888515,17440783714,50456503591,139731086307, %U A227023 371756133099,953183208702,2361809765393,5669196636680,13211336518266 %N A227023 Number of nX4 (0,1,2) arrays of permanents of 2X2 subblocks of some (n+1)X5 binary array with rows and columns of the latter in lexicographically nondecreasing order. %C A227023 Column 4 of A227025 %H A227023 R. H. Hardin, <a href="/A227023/b227023.txt">Table of n, a(n) for n = 1..37</a> %e A227023 Some solutions for n=4 %e A227023 ..0..0..1..1....0..0..1..1....0..0..0..1....0..0..0..0....0..0..0..1 %e A227023 ..0..1..0..0....0..1..0..0....0..0..1..0....0..0..1..0....0..0..0..2 %e A227023 ..2..0..0..0....1..1..0..1....0..1..0..0....0..2..0..0....0..0..0..2 %e A227023 ..2..0..0..1....0..0..2..2....0..2..0..0....1..0..1..0....0..0..1..1 %K A227023 nonn %O A227023 1,1 %A A227023 _R. H. Hardin_ Jun 27 2013