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A199164 G.f.: exp( Sum_{n>=1} (x^n/n) / [Sum_{k=0..n} C(n,k)^2*(-x)^k] ). 0
1, 1, 2, 5, 17, 77, 448, 3274, 29326, 313768, 3929226, 56701093, 930803798, 17196523994, 354410799300, 8087797118417, 203054496653329, 5577055299461291, 166745207015271392, 5403112484148713170, 188998781647795395932, 7111266811914520345796 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..21.

EXAMPLE

G.f.: A(x) = 1 + x + 2*x^2 + 5*x^3 + 17*x^4 + 77*x^5 + 448*x^6 +...

where

log(A(x)) = x/(1-x) + (x^2/2)/(1-2^2*x+x^2) + (x^3/3)/(1-3^2*x+3^2*x^2-x^3) + (x^4/4)/(1-4^2*x+6^2*x^2-4^2*x^3+x^4) + (x^5/5)/(1-5^2*x+10^2*x^2-10^2*x^3+5^2*x^4-x^5) +...

PROG

(PARI) {a(n)=local(A=1+x); for(i=1, n, A=exp(sum(m=1, n, x^m/m/sum(k=0, m, binomial(m, k)^2*(-x)^k+x*O(x^n))))); polcoeff(A, n)}

CROSSREFS

Sequence in context: A279208 A099825 A014288 * A184509 A020096 A187245

Adjacent sequences:  A199161 A199162 A199163 * A199165 A199166 A199167

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Nov 03 2011

STATUS

approved

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Last modified July 18 15:37 EDT 2019. Contains 325144 sequences. (Running on oeis4.)