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A033766
Number of prime divisors (counted without multiplicity) of A138613(n).
2
1, 1, 2, 3, 6, 8, 11, 20, 29, 47, 78, 129, 230, 400, 710, 1221
OFFSET
1,3
COMMENTS
The old entry with this sequence number was a duplicate of A035162.
MATHEMATICA
PrimeNu[NestList[DivisorSigma[2, #]&, 2, 12]] (* Harvey P. Dale, Aug 19 2017 *)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Sep 20 2008
EXTENSIONS
a(10)-a(12) from Donovan Johnson, Nov 17 2008
a(13)-a(16) from Daniel Suteu, Dec 11 2019
STATUS
approved