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 A214901 #7 Jul 22 2025 23:19:22 %S A214901 4,6,14,50,242,1682,13442,134402,1612802,22579202,361267202, %T A214901 6864076802,144145612802,3459494707202,93406357094402, %U A214901 2802190712832002,92472293523456002,3421474860367872002,136858994414714880002 %N A214901 Number of nXnXn triangular 0..3 arrays with every horizontal row nondecreasing and having the same average value. %C A214901 Column 3 of A214906 %H A214901 R. H. Hardin, <a href="/A214901/b214901.txt">Table of n, a(n) for n = 1..89</a> %e A214901 Some solutions for n=4 %e A214901 .....1........1........1........2........1........2........1........1 %e A214901 ....1.1......1.1......0.2......2.2......0.2......2.2......0.2......1.1 %e A214901 ...1.1.1....0.1.2....0.0.3....0.3.3....0.0.3....1.2.3....0.1.2....1.1.1 %e A214901 ..0.1.1.2..0.1.1.2..0.1.1.2..0.2.3.3..1.1.1.1..0.2.3.3..0.0.2.2..0.0.2.2 %K A214901 nonn %O A214901 1,1 %A A214901 _R. H. Hardin_ Jul 29 2012