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 A195231 #8 Jul 22 2025 12:41:41 %S A195231 8,50,610,14536,681942,63338492,11683832092,4290676097374, %T A195231 3142339851746238,4595720660886942892,13436641716584454488144, %U A195231 78603060373509486868646762,920680713893261032002755485080 %N A195231 Number of lower triangles of an n X n 0..7 array with each element differing from all of its diagonal, vertical, antidiagonal and horizontal neighbors by one or less. %C A195231 Column 7 of A195232 %H A195231 R. H. Hardin, <a href="/A195231/b195231.txt">Table of n, a(n) for n = 1..15</a> %e A195231 Some solutions for n=4 %e A195231 ..1........5........0........1........1........6........7........5 %e A195231 ..0.1......6.5......1.0......2.2......2.1......5.6......7.6......5.4 %e A195231 ..1.1.2....6.6.5....0.1.1....2.2.2....1.2.2....6.6.5....6.7.6....5.4.4 %e A195231 ..0.1.1.2..6.6.6.6..1.0.1.2..2.1.2.2..1.1.1.2..6.6.6.6..6.6.6.7..5.4.4.3 %K A195231 nonn %O A195231 1,1 %A A195231 _R. H. Hardin_ Sep 13 2011