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A156239 Smallest octagonal number with n distinct prime factors. +0
4
8, 21, 280, 1680, 38760, 326040, 10986360, 185040240, 4897368840, 383246454360, 13143876816840, 376306806515640, 27961718389364760, 3250163645572822440, 152582219844376633080, 6202664616058189439160 (list; graph; listen)
OFFSET

1,1
LINKS

Eric Weisstein's World of Mathematics, Octagonal Numbers.

EXAMPLE

a(9) = 4897368840 = 2^3*3*5*7*13*17*23*31*37. 4897368840 is the smallest octagonal number with 9 distinct prime factors.

CROSSREFS

Cf. A000567, A076551, A156236, A156237, A156238.

Sequence in context: A156304 A054855 A100903 this_sequence A141369 A060390 A019281

Adjacent sequences: A156236 A156237 A156238 this_sequence A156240 A156241 A156242

KEYWORD

nonn

AUTHOR

Donovan Johnson (donovan.johnson(AT)yahoo.com), Feb 07 2009

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Last modified December 10 12:37 EST 2009. Contains 170569 sequences.

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