A229342 a(n) = sigma(n'), the sum of divisors of the arithmetic derivative of n.

1, 1, 7, 1, 6, 1, 28, 12, 8, 1, 31, 1, 13, 15, 63, 1, 32, 1, 60, 18, 14, 1, 84, 18, 24, 40, 63, 1, 32, 1, 186, 24, 20, 28, 168, 1, 32, 31, 126, 1, 42, 1, 124, 56, 31, 1, 248, 24, 78, 42, 120, 1, 121, 31, 168, 36, 32, 1, 168, 1, 48, 72, 508, 39, 62, 1, 195, 42

Offset: 2

Author

Luca Brigada Villa, Sep 24 2013

Keywords

• nonn

Comments

a(1) is undefined.

Examples

			For n=4, sigma(n') = sigma(4') = sigma(4) = 7.
For n=7, sigma(n') = sigma(7') = sigma(1) = 1.
		

Links

• Antti Karttunen, Table of n, a(n) for n = 2..20000

Crossrefs

Cf. A000203, A003415.

Cf. also A229340, A229341, A229343, A229344.

Programs

PARI

rd(n) = {local(fac); if(n<1, 0, fac=factor(n); sum(i=1, matsize(fac)[1], n*fac[i, 2]/fac[i, 1];));} \\ from A003415
a(n) = sigma(rd(n)); \\ Michel Marcus, Sep 24 2013

Formula

a(n) = A000203(A003415(n)).