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A107885
Column 0 of triangle A107884.
5
1, 3, 6, 16, 63, 351, 2609, 24636, 284631, 3909926, 62459868, 1140206571, 23453446130, 537365482536, 13583603874930, 375783149051267, 11299149697288503, 367080116280553305, 12818485840320445236
OFFSET
0,2
FORMULA
G.f.: 1 = Sum_{k>=0} a(k)*x^k*(1-x)^(3 + k*(k-1)/2).
EXAMPLE
1 = 1*(1-x)^3 + 3*x*(1-x)^3 + 6*x^2*(1-x)^4 +
16*x^3*(1-x)^6 + 63*x^4*(1-x)^9 + 351*x^5*(1-x)^13 +...
PROG
(PARI) {a(n)=polcoeff(1-sum(k=0, n-1, a(k)*x^k*(1-x+x*O(x^n))^(3+k*(k-1)/2)), n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jun 04 2005
STATUS
approved