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 A141761 Column 0 of triangle A141760. 8
 1, 1, 1, 2, 6, 26, 154, 1188, 11474, 134432, 1863168, 29936846, 548625820, 11315025894, 259733293774, 6574304470320, 182050022755386, 5477819548007438, 178054691097463354, 6220193033111607018 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS Also equals column 1 (shifted) of triangle A141760. LINKS Table of n, a(n) for n=0..19. FORMULA G.f.: 1/(1-x) = Sum_{n>=0} a(n) * x^n/(1+x)^{n*(n-1)/2}. a(n) = 1 - Sum_{j=0..n-1} a(j) * (-1)^(n-j) * C(j(j-1)/2 + n-j-1, n-j) for n>0, with a(0)=1. PROG (PARI) {a(n)=if(n==0, 1, 1 - sum(j=0, n-1, a(j)*(-1)^(n-j)*binomial(j*(j-1)/2+n-j-1, n-j)))} CROSSREFS Cf. A141760, A141762, A141763, A141764. Sequence in context: A032271 A205502 A107104 * A355206 A242574 A123306 Adjacent sequences: A141758 A141759 A141760 * A141762 A141763 A141764 KEYWORD nonn AUTHOR Paul D. Hanna, Jul 18 2008 STATUS approved

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Last modified November 29 09:50 EST 2023. Contains 367429 sequences. (Running on oeis4.)