id:A112228 - OEIS Search Results

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Product of the first n (semiprimes - 1).

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3, 15, 120, 1080, 14040, 196560, 3931200, 82555200, 1981324800, 49533120000, 1585059840000, 52306974720000, 1778437140480000, 65802174197760000, 2500482619514880000, 112521717878169600000, 5401042458152140800000 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`Semiprime analogue of A005867.`
	FORMULA	`a(n) = Prod[from i = 1 to n] (A001358(i)-1).`
	EXAMPLE	`a(10) = 3589131420212425 =` `(4-1)(6-1)(9-1)(10-1)(14-1)(15-1)(21-1)(22-1)(25-1)(26-1) = 49533120000, the product of the first 10 (semiprimes minus one).`
	CROSSREFS	`Cf. A001358, A005867.` `Sequence in context: A068052 A068859 A006454 this_sequence A093571 A093570 A107869` `Adjacent sequences: A112225 A112226 A112227 this_sequence A112229 A112230 A112231`
	KEYWORD	`easy,nonn`
	AUTHOR	`Jonathan Vos Post (jvospost3(AT)gmail.com), Nov 28 2005`

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Last modified December 19 12:50 EST 2009. Contains 171053 sequences.

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