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 A195227 #8 Jul 22 2025 12:41:11 %S A195227 4,22,246,5428,237818,20729610,3601738548,1249159521262, %T A195227 865793424024974,1200356073563114252,3331551471246807302142, %U A195227 18523112376180844925948966,206425939461681776649215679048,4613382950875473008207859661034814 %N A195227 Number of lower triangles of an n X n 0..3 array with each element differing from all of its diagonal, vertical, antidiagonal and horizontal neighbors by one or less. %C A195227 Column 3 of A195232 %H A195227 R. H. Hardin, <a href="/A195227/b195227.txt">Table of n, a(n) for n = 1..18</a> %e A195227 Some solutions for n=4 %e A195227 ..3........2........0........2........1........2........1........1 %e A195227 ..3.2......3.2......1.1......1.2......1.0......2.3......1.0......0.1 %e A195227 ..2.2.2....3.2.1....1.2.1....1.1.2....1.0.1....3.3.3....0.0.1....1.0.0 %e A195227 ..3.2.3.3..2.2.2.1..2.2.2.1..1.2.1.1..1.0.1.2..3.3.2.3..1.0.1.0..1.0.0.1 %K A195227 nonn %O A195227 1,1 %A A195227 _R. H. Hardin_ Sep 13 2011