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A066102 Number of distinct prime factors of Sigma_4[n], the sum of 4th powers of divisors of n. 2
0, 1, 2, 3, 2, 3, 2, 2, 3, 3, 2, 5, 2, 3, 3, 4, 2, 4, 3, 5, 3, 3, 2, 4, 4, 3, 4, 5, 2, 4, 3, 5, 3, 3, 3, 4, 3, 3, 3, 4, 3, 4, 4, 5, 5, 3, 3, 5, 5, 5, 3, 5, 3, 4, 3, 4, 4, 3, 4, 6, 2, 4, 5, 4, 3, 4, 3, 5, 3, 4, 2, 5, 2, 4, 6, 6, 3, 4, 4, 6, 4, 4, 4, 6, 3, 4, 3, 4, 3, 6, 3, 5, 4, 4, 4, 7, 3, 6, 5, 5, 3, 4, 2, 4, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Harry J. Smith, Table of n, a(n) for n=1..1000

FORMULA

a(n) = A001221(DivisorSigma(4, n)) = A001221(A001159(n)).

MATHEMATICA

Table[PrimeNu[DivisorSigma[4, n]], {n, 1, 50}] (* G. C. Greubel, May 08 2017 *)

PROG

(PARI) { for (n=1, 1000, a=omega(sigma(n, 4)); write("b066102.txt", n, " ", a) ) } \\ Harry J. Smith, Nov 14 2009

CROSSREFS

Cf. A001159, A001221.

Sequence in context: A296658 A276862 A175066 * A036048 A145384 A339601

Adjacent sequences:  A066099 A066100 A066101 * A066103 A066104 A066105

KEYWORD

nonn

AUTHOR

Labos Elemer, Dec 04 2001

STATUS

approved

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Last modified September 23 14:40 EDT 2021. Contains 347618 sequences. (Running on oeis4.)