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A079540
a(n) = phi(n) + d(n)*(n - phi(n)) - sigma(n).
1
0, 0, 0, 1, 0, 6, 0, 5, 2, 10, 0, 24, 0, 14, 12, 17, 0, 39, 0, 38, 16, 22, 0, 76, 4, 26, 14, 52, 0, 112, 0, 49, 24, 34, 20, 137, 0, 38, 28, 118, 0, 156, 0, 80, 72, 46, 0, 212, 6, 107, 36, 94, 0, 186, 28, 160, 40, 58, 0, 376, 0, 62, 94, 129, 32, 244, 0, 122, 48, 248, 0, 405, 0, 74, 126
OFFSET
1,6
COMMENTS
It is known that a(n) >= 0 for n >= 1.
REFERENCES
D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 10.
LINKS
MATHEMATICA
Array[#2 + #3 (#1 - #2) - #4 & @@ {#, EulerPhi@ #, DivisorSigma[0, #], DivisorSigma[1, #]} &, 75] (* Michael De Vlieger, Feb 25 2018 *)
PROG
(PARI) A079540(n) = (eulerphi(n) + numdiv(n)*(n - eulerphi(n)) - sigma(n)); \\ Antti Karttunen, Feb 25 2018
(Magma) [EulerPhi(n) + DivisorSigma(0, n)*(n - EulerPhi(n)) - DivisorSigma(1, n): n in [1..80]]; // G. C. Greubel, Jan 15 2019
(Sage) [euler_phi(n) + sigma(n, 0)*(n - euler_phi(n)) - sigma(n, 1) for n in (1..80)] # G. C. Greubel, Jan 15 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 23 2003
STATUS
approved