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A087652 Product of nonprime divisors of n. +0
2
1, 1, 1, 4, 1, 6, 1, 32, 9, 10, 1, 288, 1, 14, 15, 512, 1, 972, 1, 800, 21, 22, 1, 55296, 25, 26, 243, 1568, 1, 27000, 1, 16384, 33, 34, 35, 1679616, 1, 38, 39, 256000, 1, 74088, 1, 3872, 6075, 46, 1, 42467328, 49, 12500, 51, 5408, 1, 1417176, 55, 702464, 57, 58 (list; graph; listen)
OFFSET

1,4

COMMENT

a(n) = 1 if n=1 or n is prime; a(n) = n if n=1 or n is semiprime (A001358).

EXAMPLE

n=12: nonprime divisors = {4,6,12}: a(12)=4*6*12=288.

CROSSREFS

Cf. A023890, A033273.

Sequence in context: A005451 A135683 A113520 this_sequence A072195 A032310 A032220

Adjacent sequences: A087649 A087650 A087651 this_sequence A087653 A087654 A087655

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Sep 25 2003

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Last modified November 29 12:46 EST 2009. Contains 167659 sequences.


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