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 A219074 #6 Jul 23 2025 00:12:34 %S A219074 9,165,2321,32945,477309,6879341,99118753,1428782305,20594013941, %T A219074 296830835781,4278398369137,61667023808785,888841954030797, %U A219074 12811387949686973,184657868037699425,2661579521073401057 %N A219074 Hilltop maps: number of nX4 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, diagonal or antidiagonal neighbor in a random 0..1 nX4 array. %C A219074 Column 4 of A219078 %H A219074 R. H. Hardin, <a href="/A219074/b219074.txt">Table of n, a(n) for n = 1..210</a> %F A219074 Empirical: a(n) = 11*a(n-1) +33*a(n-2) +233*a(n-3) +13*a(n-4) -31*a(n-5) -657*a(n-6) -321*a(n-7) -288*a(n-8) -64*a(n-9) +64*a(n-10) %e A219074 Some solutions for n=3 %e A219074 ..1..1..0..1....0..1..0..0....1..1..0..0....0..0..1..1....1..1..1..0 %e A219074 ..1..1..1..1....0..1..1..1....1..1..1..1....0..1..1..0....0..0..1..1 %e A219074 ..0..0..1..1....0..0..1..0....1..0..0..0....1..0..1..1....1..1..1..0 %K A219074 nonn %O A219074 1,1 %A A219074 _R. H. Hardin_ Nov 11 2012