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A088737 Number of semiprime divisors of n-th composite number. 1
1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 1, 2, 3, 1, 1, 1, 1, 3, 1, 1, 2, 3, 2, 2, 1, 2, 1, 2, 1, 2, 2, 1, 2, 1, 1, 4, 1, 2, 1, 1, 3, 2, 1, 3, 3, 1, 2, 2, 1, 3, 2, 1, 1, 4, 1, 1, 1, 2, 4, 1, 2, 1, 1, 1, 2, 2, 2, 3, 3, 2, 3, 1, 3, 3, 1, 2, 3, 1, 2, 2, 1, 1, 4, 1, 1, 1, 2, 1, 4, 1, 1, 3, 4, 1, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

Table of n, a(n) for n=1..102.

FORMULA

a(n) = A056170(n) + A001221(n)*(A001221(n)-1)/2.

CROSSREFS

Cf. A088738, A002808, A001358.

Sequence in context: A307848 A255326 A085424 * A318434 A321455 A096309

Adjacent sequences:  A088734 A088735 A088736 * A088738 A088739 A088740

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Oct 12 2003

STATUS

approved

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Last modified February 17 02:22 EST 2020. Contains 331976 sequences. (Running on oeis4.)