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 A187982 #15 Jun 15 2025 16:07:56 %S A187982 0,3,7,22,82,260,912,3158,10920,38385,134652,474953,1680801,5960094, %T A187982 21192029,75492493,269409262,963003740,3447075784,12354841859, %U A187982 44333177653,159250306113,572602762173,2060689223094,7422109110741,26752896159623,96498088175421,348296867524920,1257893866073062,4545530514677703,16434464166065112 %N A187982 Number of nondecreasing arrangements of n numbers x(i) in -(n+1)..(n+1) with the sum of sign(x(i))*2^|x(i)| zero. %e A187982 Some solutions for n=4: %e A187982 .-5...-3...-5...-4...-4...-4...-5...-4...-5...-4...-3...-3...-2...-3...-2...-5 %e A187982 .-5...-2...-2...-4...-3...-3...-4...-1...-1....2....1...-1...-1...-2....0...-3 %e A187982 ..5...-2....2....4....3...-3....4....1....1....2....1....1....1....2....0....3 %e A187982 ..5....4....5....4....4....5....5....4....5....3....2....3....2....3....1....5 %Y A187982 Column 3 of A187988. %K A187982 nonn %O A187982 1,2 %A A187982 _R. H. Hardin_, Mar 18 2011 %E A187982 More terms from _R. J. Mathar_, May 11 2023