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 A141761 Column 0 of triangle A141760. 8

%I

%S 1,1,1,2,6,26,154,1188,11474,134432,1863168,29936846,548625820,

%T 11315025894,259733293774,6574304470320,182050022755386,

%U 5477819548007438,178054691097463354,6220193033111607018

%N Column 0 of triangle A141760.

%C Also equals column 1 (shifted) of triangle A141760.

%F G.f.: 1/(1-x) = Sum_{n>=0} a(n) * x^n/(1+x)^{n*(n-1)/2}.

%F 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.

%o (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)))}

%Y Cf. A141760, A141762, A141763, A141764.

%K nonn

%O 0,4

%A _Paul D. Hanna_, Jul 18 2008

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Last modified April 4 23:14 EDT 2020. Contains 333238 sequences. (Running on oeis4.)