A193321 - OEIS

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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, 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 + 2x^2 + 6x^3 + 23x^4 + 106x^5 + 565x^6 +...` `where` `A(x) = 1 + x(1-x)/(1-2x) + x^2(1-x)(1-2x)/((1-2x)(1-4x)) + x^3(1-x)(1-2x)(1-3x)/((1-2x)(1-4x)(1-6*x)) +...`
	PROG	`(PARI) {a(n)=polcoeff(sum(m=0, n, x^mprod(k=1, m, (1-kx)/(1-(2k)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.)