A094574 - OEIS

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A094574

Number of (<=2)-covers of an n-set.

1, 1, 5, 40, 457, 6995, 136771, 3299218, 95668354, 3268445951, 129468914524, 5868774803537, 301122189141524, 17327463910351045, 1109375488487304027, 78484513540137938209, 6098627708074641312182, 517736625823888411991202 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,3`
	FORMULA	`Row sums of A094573. E.g.f: exp(-1-1/2(exp(x)-1))Sum(exp(xbinomial(n+1, 2))/n!, n=0..infinity) or exp((1-exp(x))/2)Sum(A094577 (n)*(x/2)^n/n!, n=0..infinity).`
	CROSSREFS	`Cf. A002718, A020554.` `Sequence in context: A000359 A121886 A052868 * A090362 A201366 A198247` `Adjacent sequences: A094571 A094572 A094573 * A094575 A094576 A094577`
	KEYWORD	`nonn`
	AUTHOR	`Goran Kilibarda, Vladeta Jovovic (vladeta(AT)eunet.rs), May 12 2004`

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Last modified February 17 14:19 EST 2012. Contains 206038 sequences.