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 A188227 #8 Jul 22 2025 11:03:25 %S A188227 1,3,12,81,598,4859,41748,374820,3475284,33053399,320869264, %T A188227 3167899567,31721907390,321494911644,3292220700520,34018798556265, %U A188227 354312456839426,3716173628641396,39220841304052510,416264662788000213 %N A188227 Number of nondecreasing arrangements of n numbers in -(2n-2)..(2n-2) with sum zero and not more than two numbers equal. %C A188227 Diagonal of A188236 %H A188227 R. H. Hardin, <a href="/A188227/b188227.txt">Table of n, a(n) for n = 1..22</a> %e A188227 Some solutions for n=4 %e A188227 .-1...-3...-3...-3...-4...-5...-6...-5...-4...-5...-3...-3...-2...-6...-2...-4 %e A188227 .-1....0...-2...-1...-1...-2...-1....0....1...-1...-1...-3...-2...-4...-1...-4 %e A188227 ..1....1....0....1...-1....1....2....2....1....2....2....3....2....4....0....2 %e A188227 ..1....2....5....3....6....6....5....3....2....4....2....3....2....6....3....6 %K A188227 nonn %O A188227 1,2 %A A188227 _R. H. Hardin_ Mar 24 2011