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 A188502 #7 Jul 22 2025 11:13:49 %S A188502 7,49,229,971,4351,20124,92597,423074,1932355,8836938,40424590, %T A188502 184890099,845559045,3867059514,17685848557,80885615913,369926354240, %U A188502 1691838530486,7737537171921,35387239493020,161841764228828,740175150497968 %N A188502 Number of nX3 binary arrays without the pattern 0 1 0 diagonally, vertically or horizontally. %C A188502 Column 3 of A188508 %H A188502 R. H. Hardin, <a href="/A188502/b188502.txt">Table of n, a(n) for n = 1..200</a> %F A188502 Empirical: a(n)=7*a(n-1)-21*a(n-2)+59*a(n-3)-82*a(n-4)+97*a(n-5)-14*a(n-6)-148*a(n-7)+166*a(n-8)-153*a(n-9)-158*a(n-10)+340*a(n-11)+164*a(n-12)-296*a(n-13)-87*a(n-14)+115*a(n-15)+13*a(n-16)-a(n-17)+6*a(n-18)-5*a(n-19)-6*a(n-20)+4*a(n-21)+a(n-23) %e A188502 Some solutions for 4X3 %e A188502 ..1..1..1....1..0..1....1..0..1....1..1..0....1..1..1....1..0..0....1..1..1 %e A188502 ..1..0..0....1..0..1....0..0..1....0..0..0....1..1..1....0..0..0....0..0..1 %e A188502 ..1..0..0....1..0..1....0..1..1....0..0..0....0..0..0....1..0..0....0..0..1 %e A188502 ..1..0..1....1..1..1....0..1..1....1..0..0....0..0..0....1..0..0....1..1..0 %K A188502 nonn %O A188502 1,1 %A A188502 _R. H. Hardin_ Apr 02 2011