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 A187980 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 1
 0, 1, 3, 9, 36, 117, 411, 1452, 5040, 17829, 62870, 222458, 789895, 2808018, 10006020, 35713288, 127657287, 456975112, 1637845137, 5876993799, 21110257429, 75900966585, 273140226328, 983733709424, 3545658087397, 12788512426396, 46155740640489, 166684398100813, 602296651467057, 2177492178467267, 7876245417001355 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Column 1 of A187988 LINKS Table of n, a(n) for n=1..31. EXAMPLE All solutions for n=3 .-1...-2...-1 .-1....1....0 ..2....1....0 CROSSREFS Sequence in context: A125792 A223310 A149020 * A057390 A183495 A185162 Adjacent sequences: A187977 A187978 A187979 * A187981 A187982 A187983 KEYWORD nonn AUTHOR R. H. Hardin Mar 18 2011 EXTENSIONS More terms from R. J. Mathar, May 11 2023 STATUS approved

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Last modified July 20 18:59 EDT 2024. Contains 374459 sequences. (Running on oeis4.)