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 A202122 #7 Jun 02 2025 07:24:08 %S A202122 13,127,967,5509,32267,188505,1104357,6471075,37917347,222179581, %T A202122 1301902689,7628745319,44701958081,261938834035,1534876473727, %U A202122 8993877595975,52701197650513,308811879264259,1809537203539017 %N A202122 Number of -6..6 arrays of n elements with first, second and third differences also in -6..6. %C A202122 Column 6 of A202124 %H A202122 R. H. Hardin, <a href="/A202122/b202122.txt">Table of n, a(n) for n = 1..210</a> %e A202122 Some solutions for n=5 %e A202122 .-4...-3....0...-3....0...-5....4...-1...-1...-5....3....2...-4...-6....3....1 %e A202122 .-1...-5...-5....1....4...-6...-2....2...-4...-1...-3....5...-3...-6....4....2 %e A202122 ..2...-5...-6....5....2...-3...-3....4...-2....2...-5....2...-4...-1....2....0 %e A202122 ..4...-5...-4....5...-2...-1...-4....4....1....3...-1...-1...-2....4....0...-2 %e A202122 ..3....0...-2....2...-4....5...-3....5....2....1....3...-4....1....5...-6...-5 %K A202122 nonn %O A202122 1,1 %A A202122 _R. H. Hardin_ Dec 11 2011