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 A218661 #6 Jul 23 2025 00:03:11 %S A218661 31,3519,199489,12383361,775176415,48231228511,3004025019009, %T A218661 187110346460865,11653760352498463,725837910289490239, %U A218661 45207782461323582145,2815700819921566341313,175371845132587985115103 %N A218661 Hilltop maps: number of nX6 binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..1 nX6 array. %C A218661 Column 6 of A218663 %H A218661 R. H. Hardin, <a href="/A218661/b218661.txt">Table of n, a(n) for n = 1..207</a> %F A218661 Empirical: a(n) = 44*a(n-1) +867*a(n-2) +16044*a(n-3) +52184*a(n-4) +219408*a(n-5) -2896552*a(n-6) +917568*a(n-7) -25421202*a(n-8) +135406584*a(n-9) -107845290*a(n-10) +627256872*a(n-11) -2093643936*a(n-12) +1109711664*a(n-13) -4042730304*a(n-14) +9244418112*a(n-15) +947037339*a(n-16) +1414420380*a(n-17) -4269096657*a(n-18) -173831508*a(n-19) -21695040*a(n-20) +555393024*a(n-21) %e A218661 Some solutions for n=3 %e A218661 ..0..1..0..1..0..1....0..1..0..1..0..1....0..1..0..0..1..1....0..1..1..1..1..0 %e A218661 ..0..0..0..1..1..1....1..1..0..0..0..1....1..0..0..0..0..0....1..0..0..1..1..1 %e A218661 ..1..1..0..0..0..1....0..1..0..1..0..1....1..0..1..0..0..1....1..1..0..1..1..1 %K A218661 nonn %O A218661 1,1 %A A218661 _R. H. Hardin_ Nov 04 2012