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A141242
a(n) is the number of divisors of the n-th positive integer with a prime number of divisors. In other words, a(n) is the number of divisors of A009087(n).
7
2, 2, 3, 2, 2, 3, 2, 2, 5, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 7, 2, 2, 2, 2, 5, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2
OFFSET
1,1
COMMENTS
A009087(n) is of the form p^(a(n)-1), where p is some prime.
LINKS
FORMULA
a(n) = A000005(A009087(n)).
MATHEMATICA
DivisorSigma[0, #] &@ Select[Range@ 500, PrimeQ@ DivisorSigma[0, #] &] (* Michael De Vlieger, Aug 19 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Jun 16 2008
EXTENSIONS
Extended by Ray Chandler, Jun 25 2009
STATUS
approved