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 A218349 #6 Jul 22 2025 23:55:03 %S A218349 5,41,291,2069,14811,105913,757305,5415209,38722037,276885777, %T A218349 1979899795,14157473937,101234450215,723887182917,5176228570197, %U A218349 37013146305509,264666248964889,1892522801570497,13532675845407459,96766768350125913 %N A218349 Hilltop maps: number of nX3 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or vertical neighbor in a random 0..1 nX3 array. %C A218349 Column 3 of A218354 %H A218349 R. H. Hardin, <a href="/A218349/b218349.txt">Table of n, a(n) for n = 1..210</a> %F A218349 Empirical: a(n) = 6*a(n-1) +5*a(n-2) +22*a(n-3) +7*a(n-4) +8*a(n-5) -18*a(n-6) -20*a(n-7) -a(n-8) +4*a(n-9) +3*a(n-10) +a(n-12) %e A218349 Some solutions for n=3 %e A218349 ..1..1..1....1..1..0....1..1..0....1..1..1....0..0..1....1..1..1....1..1..0 %e A218349 ..0..0..1....1..1..1....1..1..1....0..1..1....1..0..1....1..1..1....0..0..0 %e A218349 ..0..1..1....0..0..0....0..1..0....1..1..0....1..0..0....0..1..0....1..1..1 %K A218349 nonn %O A218349 1,1 %A A218349 _R. H. Hardin_ Oct 26 2012