1,3

G. C. Greubel, Table of n, a(n) for n = 1..1000

a(n) = A000203(A000005(A000010(n))) = A000203(A062821(n)) = A062069(A000010(n)).

DivisorSigma[1, DivisorSigma[0, EulerPhi[Range[100]]]] (* G. C. Greubel, Dec 20 2016 *)

(PARI) vector(100, n, sigma(numdiv(eulerphi(n)))) \\ G. C. Greubel, Dec 20 2016

(MAGMA) [SumOfDivisors(NumberOfDivisors(EulerPhi(n))): n in [1..80]]; // Vincenzo Librandi, Dec 20 2016

Cf. A000005, A000010, A000203, A062069, A062821.

Sequence in context: A151664 A083503 A062069 * A027011 A267048 A326401

Adjacent sequences: A163372 A163373 A163374 * A163376 A163377 A163378

nonn

Jaroslav Krizek, Jul 25 2009

approved