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A112228 Product of the first n (semiprimes - 1). 0
3, 15, 120, 1080, 14040, 196560, 3931200, 82555200, 1981324800, 49533120000, 1585059840000, 52306974720000, 1778437140480000, 65802174197760000, 2500482619514880000, 112521717878169600000, 5401042458152140800000 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Semiprime analogue of A005867.

FORMULA

a(n) = Prod[from i = 1 to n] (A001358(i)-1).

EXAMPLE

a(10) = 3*5*8*9*13*14*20*21*24*25 =

(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 * A093571 A093570 A107869

Adjacent sequences:  A112225 A112226 A112227 * A112229 A112230 A112231

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post (jvospost3(AT)gmail.com), Nov 28 2005

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Last modified February 14 22:12 EST 2012. Contains 205670 sequences.