id:A111601 - OEIS Search Results

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Exponential (binomial) convolution of A001818 (with interspersed zeros) and A000142 (factorials).

+0
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1, 2, 9, 36, 225, 1350, 11025, 88200, 893025, 8930250, 108056025, 1296672300, 18261468225, 255660555150, 4108830350625, 65741285610000, 1187451971330625, 21374135483951250, 428670161650355625, 8573403233007112500 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`E.g.f. (1/sqrt(1-x^2))x/(1-x).` `a(n)= n!sum(binomial(2k, k)/(4^k), k=0..floor((n-1)/2)).` `a(2k+1) = A111595(2k+2, 0)= ((2k+1)!!)^2 = A001818(k+1), k>=0.`
	CROSSREFS	`Second column (m=1) of triangle \|A111595\|.` `Adjacent sequences: A111598 A111599 A111600 this_sequence A111602 A111603 A111604` `Sequence in context: A137955 A003161 A101610 this_sequence A037553 A012493 A106851`
	KEYWORD	`nonn,easy`
	AUTHOR	`Wolfdieter Lang (wolfdieter.lang_AT_physik_DOT_uni-karlsruhe_DOT_de), Aug 23 2005`

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Last modified October 9 14:06 EDT 2008. Contains 144831 sequences.

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