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A193321 G.f.: Sum_{n>=0} x^n*Product_{k=1..n} (1 - k*x) / (1 - (2*k)*x). 1
1, 1, 2, 6, 23, 106, 565, 3391, 22523, 163578, 1286990, 10886149, 98377648, 944863003, 9602092037, 102856190049, 1157496371816, 13644751751698, 168052771354837, 2157537327051316, 28814062411243931, 399551143081559391, 5742819361050324227 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 0..270

EXAMPLE

G.f.: A(x) = 1 + x + 2*x^2 + 6*x^3 + 23*x^4 + 106*x^5 + 565*x^6 +...

where

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

PROG

(PARI) {a(n)=polcoeff(sum(m=0, n, x^m*prod(k=1, m, (1-k*x)/(1-(2*k)*x +x*O(x^n)))), n)}

CROSSREFS

Sequence in context: A165489 A192315 A288912 * A263780 A125273 A187761

Adjacent sequences:  A193318 A193319 A193320 * A193322 A193323 A193324

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jul 22 2011

STATUS

approved

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Last modified February 19 18:22 EST 2019. Contains 320327 sequences. (Running on oeis4.)