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 A218586 #7 Jul 22 2025 23:59:10 %S A218586 1,13,449,56629,28543403,57707873919,467122877883141, %T A218586 15124271280844676313,1958173356335852318774549, %U A218586 1013875932726564267833657180687 %N A218586 Hilltop maps: number of n X n binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or antidiagonal neighbor in a random 0..2 n X n array. %C A218586 Diagonal of A218592 %e A218586 Some solutions for n=3 %e A218586 ..1..1..0....1..1..0....0..0..1....0..1..0....1..0..0....1..0..0....1..0..1 %e A218586 ..1..0..1....0..0..1....0..0..1....1..1..0....0..1..1....1..0..0....1..0..1 %e A218586 ..0..1..1....1..0..0....0..0..0....1..1..0....1..0..1....0..1..0....1..1..1 %K A218586 nonn %O A218586 1,2 %A A218586 _R. H. Hardin_ Nov 03 2012