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 A223676 #6 Jul 23 2025 04:22:57 %S A223676 11,121,1118,9822,85663,744272,6458585,56030742,486038270,4215998078, %T A223676 36570143008,317213501163,2751542844692,23867162292347, %U A223676 207026174729348,1795765890711121,15576654086308004,135113465080900087 %N A223676 Number of nX4 0..1 arrays with rows and antidiagonals unimodal. %C A223676 Column 4 of A223680 %H A223676 R. H. Hardin, <a href="/A223676/b223676.txt">Table of n, a(n) for n = 1..210</a> %F A223676 Empirical: a(n) = 11*a(n-1) -21*a(n-2) +18*a(n-3) -114*a(n-4) +183*a(n-5) -96*a(n-6) +80*a(n-7) -65*a(n-8) +16*a(n-9) %e A223676 Some solutions for n=3 %e A223676 ..0..0..1..0....1..0..0..0....0..0..0..0....1..1..1..0....0..0..0..1 %e A223676 ..0..0..0..0....1..0..0..0....1..1..1..1....1..0..0..0....0..0..1..0 %e A223676 ..0..0..0..1....0..0..1..0....0..0..0..0....0..0..1..1....0..1..1..1 %K A223676 nonn %O A223676 1,1 %A A223676 _R. H. Hardin_ Mar 25 2013