id:A087298 - OEIS Search Results

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Exponent of 2 in factorization of (3n)!.

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	OFFSET	`1,2`
	COMMENT	`a(2n) = a(n) + 3n.`
	FORMULA	`Sum[k=1..inf, floor(3n/2^k)].`
	EXAMPLE	`(35)! = 2^11 638512875, so a(5) = 11.`
	PROGRAM	`(PARI) a(n)=valuation((3*n)!, 2)`
	CROSSREFS	`Cf. A011371 (n!), A005187 ((2n)!).` `Sequence in context: A072125 A082206 A115566 this_sequence A127958 A000414 A025357` `Adjacent sequences: A087295 A087296 A087297 this_sequence A087299 A087300 A087301`
	KEYWORD	`nonn,easy`
	AUTHOR	`Ralf Stephan (ralf(AT)ark.in-berlin.de), Oct 20 2003`

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Last modified December 16 17:18 EST 2009. Contains 170825 sequences.

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