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 A079537 a(n) = phi(2*n+1)*d(2*n+1) - sigma(2*n+1). 2
 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 (list; graph; refs; listen; history; text; internal format)
 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

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Last modified May 14 07:13 EDT 2021. Contains 343879 sequences. (Running on oeis4.)