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 A198525 #7 Jul 22 2025 12:59:26 %S A198525 52,81844,222590953,634586561196,1814002928583853,5186266567454077293, %T A198525 14827770532074166305565,42393290191915767856385826, %U A198525 121204405622972228787863169567,346529082914494875185400399625818 %N A198525 Number of nX5 0..4 arrays with values 0..4 introduced in row major order and each element equal to no more than two horizontal and vertical neighbors. %C A198525 Column 5 of A198528 %H A198525 R. H. Hardin, <a href="/A198525/b198525.txt">Table of n, a(n) for n = 1..64</a> %e A198525 Some solutions for n=4 %e A198525 ..0..0..1..2..3....0..1..2..2..0....0..1..0..2..2....0..1..1..2..3 %e A198525 ..1..1..0..1..4....1..1..0..3..1....1..1..0..3..0....1..1..0..1..2 %e A198525 ..0..0..1..2..2....0..0..1..0..3....0..0..1..0..2....0..0..1..0..4 %e A198525 ..0..0..1..0..3....0..0..1..2..1....0..0..1..3..1....0..0..1..3..3 %K A198525 nonn %O A198525 1,1 %A A198525 _R. H. Hardin_ Oct 26 2011