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 A224544 #7 Aug 30 2018 15:49:21 %S A224544 16,32,52,86,137,218,345,547,869,1385,2214,3549,5702,9178,14794,23872, %T A224544 38551,62292,100695,162821,263331,425947,689052,1114751,1803532, %U A224544 2917988,4721200,7638842,12359669,19998110,32357349,52354999,84711857,137066333 %N A224544 Number of (n+1) X 3 0..1 matrices with each 2 X 2 subblock idempotent. %C A224544 Column 2 of A224550. %H A224544 R. H. Hardin, <a href="/A224544/b224544.txt">Table of n, a(n) for n = 1..210</a> %F A224544 Empirical: a(n) = 4*a(n-1) - 5*a(n-2) + a(n-3) + 2*a(n-4) - a(n-5). %F A224544 Empirical g.f.: x*(16 - 32*x + 4*x^2 + 22*x^3 - 11*x^4) / ((1 - x)^3*(1 - x - x^2)). - _Colin Barker_, Aug 30 2018 %e A224544 Some solutions for n=3: %e A224544 ..1..1..1....0..0..0....1..1..1....1..0..0....1..0..0....1..0..0....1..0..0 %e A224544 ..0..0..0....0..0..0....0..0..0....1..0..0....1..0..0....0..0..0....1..0..1 %e A224544 ..0..0..0....0..0..0....0..0..1....1..0..0....1..0..0....0..0..0....1..0..1 %e A224544 ..0..0..0....0..1..1....0..0..1....1..0..0....0..0..0....1..1..1....1..0..1 %Y A224544 Cf. A224550. %K A224544 nonn %O A224544 1,1 %A A224544 _R. H. Hardin_, Apr 10 2013