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A323880
Number of divisors d > 1 of n such that A003415(d) divides n, where A003415 gives the arithmetic derivative of n.
2
0, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 2, 2, 1, 3, 1, 3, 2, 2, 1, 4, 1, 2, 2, 3, 1, 4, 1, 3, 2, 2, 2, 4, 1, 2, 2, 3, 1, 3, 1, 3, 2, 2, 1, 5, 1, 3, 2, 3, 1, 4, 2, 3, 2, 2, 1, 5, 1, 2, 2, 3, 2, 3, 1, 3, 2, 4, 1, 5, 1, 2, 2, 3, 2, 3, 1, 3, 2, 2, 1, 4, 2, 2, 2, 3, 1, 5, 2, 3, 2, 2, 2, 6, 1, 3, 2, 4, 1, 3, 1, 3, 3
OFFSET
1,4
FORMULA
a(n) = Sum_{d|n, d>1} [A003415(d)|n], where [ ] is the Iverson bracket, and A003415 gives the arithmetic derivative of n.
PROG
(PARI)
A003415(n) = {my(fac); if(n<1, 0, fac=factor(n); sum(i=1, matsize(fac)[1], n*fac[i, 2]/fac[i, 1]))}; \\ From A003415
A323880(n) = sumdiv(n, d, (d>1)&&!(n%A003415(d)));
CROSSREFS
Cf. A003415.
Cf. also A173441, A323878, A323879.
Sequence in context: A357859 A338731 A081757 * A338651 A033107 A354598
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 07 2019
STATUS
approved