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 A207902 #8 Jul 22 2025 20:57:42 %S A207902 2,16,102,841,13865,314721,6835345,167806116,7410251162,472676875225, %T A207902 25730176554865,1604226387312025,207661113723753822, %U A207902 40075955918500009225,5496265530262722657980,835639569395431034391481 %N A207902 Number of n X n 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 0 and 0 1 1 vertically. %C A207902 Diagonal of A207908 %e A207902 Some solutions for n=4 %e A207902 ..1..1..1..0....1..0..0..1....1..1..0..0....1..1..0..1....0..1..1..1 %e A207902 ..1..0..1..1....0..1..1..0....1..1..1..0....0..0..1..1....1..0..0..1 %e A207902 ..0..1..1..0....1..0..0..1....1..0..0..1....1..1..0..1....0..1..1..1 %e A207902 ..0..0..1..1....0..1..1..0....0..1..1..0....0..0..1..1....1..0..0..1 %K A207902 nonn %O A207902 1,1 %A A207902 _R. H. Hardin_ Feb 21 2012