A163105 a(n) = tau(sigma(tau(n))), where tau = number of divisors of n (A000005), and sigma = sum of divisors of n (A000203).
1, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 6, 2, 2, 2, 4, 2, 6, 2, 6, 2, 2, 2, 4, 3, 2, 2, 6, 2, 4, 2, 6, 2, 2, 2, 2, 2, 2, 2, 4, 2, 4, 2, 6, 6, 2, 2, 6, 3, 6, 2, 6, 2, 4, 2, 4, 2, 2, 2, 6, 2, 2, 6, 4, 2, 4, 2, 6, 2, 4, 2, 6, 2, 2, 6, 6, 2, 4, 2, 6, 4, 2, 2, 6, 2, 2, 2, 4, 2, 6, 2, 6, 2, 2, 2, 6, 2, 6, 6, 2, 2, 4, 2, 4, 4
Offset: 1
Keywords
Links
Programs
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Maple
with(numtheory) : A163105 := proc(n) tau(sigma(tau(n))) ; end: seq(A163105(n),n=1..120) ; # R. J. Mathar, Jul 27 2009
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Mathematica
With[{s = DivisorSigma}, s[0, s[1, s[0, Range[100]]]]] (* Paolo Xausa, Oct 07 2024 *) -
PARI
A163105(n) = numdiv(sigma(numdiv(n))); \\ Antti Karttunen, Jul 23 2017
Extensions
More terms from R. J. Mathar, Jul 27 2009
Name edited by Antti Karttunen, Jul 23 2017
Comments