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 A202666 #7 Jul 22 2025 16:45:44 %S A202666 23,363,2591,11413,37505,101567,238453,503849,979919,1783797,3075089, %T A202666 5067465,8035301,12330321,18389067,26749755,38062317,53112803, %U A202666 72823295,98289495,130780551,171770127,222946517,286251779,363870209,458294877 %N A202666 Number of -n..n arrays of 6 elements with first through fourth differences also in -n..n. %C A202666 Row 6 of A202664 %H A202666 R. H. Hardin, <a href="/A202666/b202666.txt">Table of n, a(n) for n = 1..121</a> %e A202666 Some solutions for n=5 %e A202666 .-2....1...-1....4....1...-2....2....4....1....4....3....3...-3....2...-3....4 %e A202666 ..1....2...-4....3....1...-3....0....1...-1....0....0...-2....1....0....1....1 %e A202666 ..0....2...-4...-1....0...-2...-1....2....0...-1....1...-3....4...-1....0....2 %e A202666 .-1....1...-2...-5....0...-1....0....5....2...-2....1...-3....4...-1...-2....3 %e A202666 .-1....2....0...-5...-2....1....1....5....3...-2...-2...-2....0...-1...-3....2 %e A202666 .-4....4....1...-1...-5....3...-1....1....4....3...-5...-3...-4...-1....0...-2 %K A202666 nonn %O A202666 1,1 %A A202666 _R. H. Hardin_ Dec 22 2011