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 A202660 #7 Jun 02 2025 07:26:26 %S A202660 9,61,323,1279,3785,11413,34171,102705,308785,928115,2790241,8389429, %T A202660 25223913,75838823,228021213,685581997,2061310319,6197655253, %U A202660 18634234069,56026786211,168453450193,506482113541,1522819068075,4578597906197 %N A202660 Number of -4..4 arrays of n elements with first through fourth differences also in -4..4. %C A202660 Column 4 of A202664 %H A202660 R. H. Hardin, <a href="/A202660/b202660.txt">Table of n, a(n) for n = 1..210</a> %e A202660 Some solutions for n=7 %e A202660 ..2....2...-1...-2....0....1....1....0...-1....3....3....4....0...-4...-3...-4 %e A202660 ..2....0...-3...-1...-1...-2....2...-2....0....2...-1....2....2...-3...-3...-4 %e A202660 ..1....0...-2...-2...-1...-3....4...-2....1....0...-1....1....4....0...-4...-4 %e A202660 .-1...-1....1...-2....0...-3....4....0....0...-1....0....1....4....1...-4...-2 %e A202660 .-2...-2....2...-2....0...-4....2....0...-2...-1....0....0....3....0...-1....0 %e A202660 .-1....0....1...-1...-1...-4....0...-2...-4...-2....0....0....1...-1....3....0 %e A202660 .-1....4...-1...-2...-1...-3....2...-4...-3...-4....0....1...-1...-3....4...-3 %K A202660 nonn %O A202660 1,1 %A A202660 _R. H. Hardin_ Dec 22 2011