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 A187987 #11 Jun 15 2025 17:10:56 %S A187987 0,8,17,72,267,915,3407,12148,43820,158361,570132,2058621,7429283, %T A187987 26823311,96904923,350182773,1266059030,4579170527,16568732508, %U A187987 59974168593,217170088270,786671363225,2850611975840,10333040668513,37467797814236,135900958160905 %N A187987 Number of nondecreasing arrangements of n numbers x(i) in -(n+6)..(n+6) with the sum of sign(x(i))*2^|x(i)| zero. %e A187987 Some solutions for n=3 %e A187987 .-1...-7...-4...-7...-8...-3...-3...-5...-6...-6...-8...-5...-4...-2...-9...-1 %e A187987 ..0....6...-4...-7...-8...-3....2...-5...-6....5....7....4....3...-2....8...-1 %e A187987 ..0....6....5....8....9....4....2....6....7....5....7....4....3....3....8....2 %Y A187987 Column 8 of A187988. %K A187987 nonn %O A187987 1,2 %A A187987 _R. H. Hardin_, Mar 18 2011 %E A187987 Terms beyond a(11) from _R. J. Mathar_, May 17 2023