A079537 a(n) = phi(2*n+1)*d(2*n+1) - sigma(2*n+1).

0, 0, 2, 4, 5, 8, 10, 8, 14, 16, 16, 20, 29, 32, 26, 28, 32, 48, 34, 40, 38, 40, 66, 44, 69, 56, 50, 88, 64, 56, 58, 112, 108, 64, 80, 68, 70, 116, 144, 76, 149, 80, 148, 104, 86, 176, 112, 168, 94, 204, 98, 100, 192, 104, 106, 136, 110, 208, 250, 240, 197, 152, 244, 124, 160

Offset

0,3

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 = 0..10000

Mathematica

Table[EulerPhi[2*n+1]*DivisorSigma[0, 2*n+1] - DivisorSigma[1, 2*n+1], {n, 0, 80}] (* G. C. Greubel, Jan 15 2019 *)

Prog

(PARI) vector(80, n,  n--; eulerphi(2*n+1)*sigma(2*n+1, 0) - sigma(2*n+1, 1)) \\ G. C. Greubel, Jan 15 2019
(Magma) [EulerPhi(2*n+1)*DivisorSigma(0, 2*n+1) - DivisorSigma(1, 2*n+1): n in [0..80]]; // G. C. Greubel, Jan 15 2019
(Sage) [euler_phi(2*n+1)*sigma(2*n+1, 0) - sigma(2*n+1, 1) for n in (0..80)] # G. C. Greubel, Jan 15 2019

Crossrefs

Cf. A000010, A000005, A000203, A079536.

Sequence in context: A095031 A100598 A191535 * A094591 A189093 A325442

Adjacent sequences: A079534 A079535 A079536 * A079538 A079539 A079540

Keyword

nonn

Author

N. J. A. Sloane, Jan 23 2003

Status

approved