login
This site is supported by donations to The OEIS Foundation.
Logo

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A112141 Product of the first n semiprimes. 13
4, 24, 216, 2160, 30240, 453600, 9525600, 209563200, 5239080000, 136216080000, 4495130640000, 152834441760000, 5349205461600000, 203269807540800000, 7927522494091200000, 364666034728195200000, 17868635701681564800000, 911300420785759804800000 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Semiprime analogue of primorial (A002110). Equivalent for product of what A062198 is for sum. Bigomega(a(n)) = the number of not necessarily distinct prime factors of a(n) = A001222(a(n)) = A005843(n) = 2*n.

FORMULA

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

EXAMPLE

a(10) = 4*6*9*10*14*15*21*22*25*26 = 136216080000, the product of the first 10 semiprimes.

CROSSREFS

Cf. A001358, A002110, A062198, A112141.

Sequence in context: A050388 A010039 A162314 * A077555 A166881 A183279

Adjacent sequences:  A112138 A112139 A112140 * A112142 A112143 A112144

KEYWORD

easy,nonn

AUTHOR

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified February 15 03:33 EST 2012. Contains 205694 sequences.