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 A219144 #6 Jul 23 2025 00:16:23 %S A219144 1,18,78,281,1072,4033,15255,57963,220068,835820,3172817,12044346, %T A219144 45722019,173574485,658947323,2501581220,9496787730,36052730049, %U A219144 136867284190,519590670019,1972527813429,7488329193659,28428025632710 %N A219144 Unchanging value maps: number of 3Xn binary arrays indicating the locations of corresponding elements unequal to no horizontal, diagonal or antidiagonal neighbor in a random 0..2 3Xn array. %C A219144 Row 3 of A219142 %H A219144 R. H. Hardin, <a href="/A219144/b219144.txt">Table of n, a(n) for n = 1..40</a> %F A219144 Empirical: a(n) = 4*a(n-1) -8*a(n-3) +17*a(n-4) +17*a(n-5) -29*a(n-6) -13*a(n-7) +9*a(n-8) -31*a(n-9) -26*a(n-10) +30*a(n-11) -3*a(n-12) +6*a(n-13) +17*a(n-14) -3*a(n-15) +3*a(n-16) -2*a(n-17) for n>18 %e A219144 Some solutions for n=3 %e A219144 ..1..0..1....1..0..1....0..0..1....0..0..1....1..0..0....0..0..0....0..0..0 %e A219144 ..0..0..1....0..0..1....0..0..1....1..0..1....1..0..0....1..0..1....0..0..1 %e A219144 ..1..0..1....0..0..1....0..0..1....1..0..0....0..0..1....0..0..1....1..0..1 %K A219144 nonn %O A219144 1,2 %A A219144 _R. H. Hardin_ Nov 12 2012