A079535 a(n) = phi(n)*d(n) - n.

0, 0, 1, 2, 3, 2, 5, 8, 9, 6, 9, 12, 11, 10, 17, 24, 15, 18, 17, 28, 27, 18, 21, 40, 35, 22, 45, 44, 27, 34, 29, 64, 47, 30, 61, 72, 35, 34, 57, 88, 39, 54, 41, 76, 99, 42, 45, 112, 77, 70, 77, 92, 51, 90, 105, 136, 87, 54, 57, 132, 59, 58, 153, 160, 127, 94, 65, 124, 107, 122, 69

Offset: 1

Author

N. J. A. Sloane, Jan 23 2003

Keywords

• nonn

Comments

It is known that a(n) >= 0.

References

• D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 10.

Links

• G. C. Greubel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000010, A000005, A062355.

Programs

Magma

[EulerPhi(n)*DivisorSigma(0,n) - n: n in [1..80]]; // G. C. Greubel, Jan 14 2019

Mathematica

Table[EulerPhi[n]*DivisorSigma[0, n] - n, {n, 1, 80}] (* G. C. Greubel, Jan 14 2019 *)

PARI

vector(80, n, eulerphi(n)*sigma(n,0) - n) \\ G. C. Greubel, Jan 14 2019

Sage

[euler_phi(n)*sigma(n, 0) - n for n in (1..80)] # G. C. Greubel, Jan 14 2019