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 A221320 #6 Jun 02 2025 08:15:50 %S A221320 1,2,7,14,30,76,188,444,1075,2656,6499,15904,39257,97012,239836, %T A221320 594484,1476309,3670470,9137025,22774518,56827616,141930316,354803429, %U A221320 887699408,2222657891,5569118954,13963300515,35031289966,87937202200,220862633536 %N A221320 Number of nonnegative integer arrays of length n summing to n without equal adjacent values modulo 7. %C A221320 Column 7 of A221321 %H A221320 R. H. Hardin, <a href="/A221320/b221320.txt">Table of n, a(n) for n = 1..210</a> %e A221320 Some solutions for n=10 %e A221320 ..1....0....0....3....0....1....0....0....1....1....2....1....1....1....1....0 %e A221320 ..2....2....2....2....2....0....3....2....3....0....0....0....0....0....0....1 %e A221320 ..1....0....3....1....0....1....1....1....0....1....1....1....1....1....2....2 %e A221320 ..2....2....0....0....1....0....0....0....1....0....2....4....2....3....0....0 %e A221320 ..0....0....1....1....3....3....2....2....3....2....1....1....1....0....1....1 %e A221320 ..1....2....0....0....0....0....0....0....0....1....0....0....0....2....0....0 %e A221320 ..2....0....1....1....1....4....3....2....1....4....2....2....2....0....3....3 %e A221320 ..0....2....0....0....0....0....0....1....0....0....0....0....1....2....0....0 %e A221320 ..1....0....1....2....3....1....1....2....1....1....2....1....0....1....2....3 %e A221320 ..0....2....2....0....0....0....0....0....0....0....0....0....2....0....1....0 %K A221320 nonn %O A221320 1,2 %A A221320 _R. H. Hardin_ Jan 10 2013