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A058062
Number of distinct prime factors of sigma(n), the sum of the divisors of n.
8
0, 1, 1, 1, 2, 2, 1, 2, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 3, 1, 2, 2, 3, 1, 3, 2, 2, 3, 2, 1, 2, 2, 2, 2, 2, 2, 3, 2, 3, 3, 2, 2, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 3, 2, 3, 3, 3, 2, 2, 2, 1, 3, 2, 2, 3, 2, 2, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 1, 3, 3, 2, 2, 3, 3, 3, 3, 3, 2, 3, 1, 2, 3, 3, 2, 2, 3, 2, 3, 2, 2, 4, 2
OFFSET
1,5
LINKS
FORMULA
a(n) = A001221(A000203(n)).
EXAMPLE
n=81, sigma(81) = 81+27+9+3+1 = 121 = 11^2, so a(81) = 1.
MATHEMATICA
Table[PrimeNu[DivisorSigma[1, n]], {n, 50}] (* G. C. Greubel, May 20 2017 *)
PROG
(PARI) for(n=1, 50, print1(omega(sigma(n)), ", ")) \\ G. C. Greubel, May 20 2017
CROSSREFS
Sequence in context: A091267 A003643 A092788 * A102820 A355717 A024317
KEYWORD
nonn
AUTHOR
Labos Elemer, Nov 23 2000
EXTENSIONS
Offset corrected by Sean A. Irvine, Jul 22 2022
STATUS
approved