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 A189618 #7 Jul 22 2025 11:51:14 %S A189618 8,64,292,1164,5238,25046,116100,526418,2403976,11065442,50854642, %T A189618 233077382,1068505272,4902990456,22498260976,103204910914, %U A189618 473409837692,2171794653270,9963444579674,45707359388096,209680588779494 %N A189618 Number of 3Xn binary arrays without the pattern 0 1 0 diagonally, antidiagonally or horizontally. %C A189618 Row 3 of A189617 %H A189618 R. H. Hardin, <a href="/A189618/b189618.txt">Table of n, a(n) for n = 1..200</a> %F A189618 Empirical: a(n) = 5*a(n-1) -8*a(n-2) +24*a(n-3) +35*a(n-4) -90*a(n-5) +103*a(n-6) -92*a(n-7) -479*a(n-8) +312*a(n-9) +411*a(n-10) -97*a(n-11) +212*a(n-12) -154*a(n-13) -300*a(n-14) +72*a(n-15) -175*a(n-16) +42*a(n-17) -20*a(n-18) +4*a(n-19) %e A189618 Some solutions for 3X3 %e A189618 ..0..0..1....0..1..1....1..0..1....0..0..1....1..1..0....0..1..1....1..1..0 %e A189618 ..0..0..0....0..0..0....0..1..1....1..1..0....1..0..0....1..0..1....0..0..0 %e A189618 ..0..1..1....1..0..1....0..1..1....0..0..1....1..1..1....0..0..0....1..1..0 %K A189618 nonn %O A189618 1,1 %A A189618 _R. H. Hardin_ Apr 24 2011