A079539 a(n) = sigma[k](n) - phi(n)^k - d(n)^k for k=3.

-1, 0, 12, 38, 54, 180, 120, 457, 514, 1006, 324, 1764, 462, 2816, 2952, 4044, 810, 6381, 1020, 8470, 7840, 10924, 1512, 15356, 7724, 17990, 14544, 23168, 2430, 30728, 2784, 33137, 29232, 40066, 29456, 52804, 3990, 55844, 47656, 69102, 4914, 84448, 5412, 89020

Offset

1,3

Comments

It is known that a(n) >= 0 for n >= 2.

References

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

Links

T. D. Noe, Table of n, a(n) for n=1..10000

Formula

a(n) = 3*n^2 - 3*n - 6 for prime n. - T. D. Noe, Dec 19 2006

Mathematica

Table[DivisorSigma[3, n] - EulerPhi[n]^3 - DivisorSigma[0, n]^3, {n, 80}] (* G. C. Greubel, Jan 15 2019 *)

Prog

(PARI) vector(80, n, sigma(n, 3) - eulerphi(n)^3 - numdiv(n)^3) \\ G. C. Greubel, Jan 15 2019
(Magma) [DivisorSigma(3, n) - EulerPhi(n)^3 - DivisorSigma(0, n)^3: n in [1..80]]; // G. C. Greubel, Jan 15 2019
(Sage) [sigma(n, 3) - euler_phi(n)^3 - sigma(n, 0)^3 for n in (1..80)] # G. C. Greubel, Jan 15 2019

Crossrefs

Cf. A000010, A000005, A000203, A046520 (for k=1), A079538.

Sequence in context: A043117 A039294 A043897 * A242720 A212510 A213490

Adjacent sequences: A079536 A079537 A079538 * A079540 A079541 A079542

Keyword

sign

Author

N. J. A. Sloane, Jan 23 2003

Status

approved