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 A221318 #6 Jun 02 2025 08:15:36 %S A221318 1,2,7,14,30,76,185,430,1044,2544,6154,15002,36691,89918,220728, %T A221318 543054,1338428,3302916,8162806,20197554,50030332,124053930,307882669, %U A221318 764770230,1901144731,4729494390,11773517941,29327102054,73094698149,182280159290 %N A221318 Number of nonnegative integer arrays of length n summing to n without equal adjacent values modulo 5. %C A221318 Column 5 of A221321 %H A221318 R. H. Hardin, <a href="/A221318/b221318.txt">Table of n, a(n) for n = 1..210</a> %e A221318 Some solutions for n=8 %e A221318 ..0....0....0....1....0....1....0....1....1....0....0....0....0....1....1....1 %e A221318 ..1....2....1....3....1....0....1....3....2....2....3....4....2....3....4....3 %e A221318 ..0....0....3....0....2....1....2....0....1....0....0....0....1....1....0....0 %e A221318 ..3....1....0....1....3....3....0....2....0....4....3....1....0....0....1....1 %e A221318 ..0....0....1....0....1....2....1....1....1....1....1....0....2....1....0....2 %e A221318 ..1....2....2....2....0....0....2....0....0....0....0....1....0....0....1....0 %e A221318 ..3....3....1....1....1....1....0....1....2....1....1....0....3....2....0....1 %e A221318 ..0....0....0....0....0....0....2....0....1....0....0....2....0....0....1....0 %K A221318 nonn %O A221318 1,2 %A A221318 _R. H. Hardin_ Jan 10 2013