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A057000 a(n) = phi(n+1) - phi(n). 5
0, 1, 0, 2, -2, 4, -2, 2, -2, 6, -6, 8, -6, 2, 0, 8, -10, 12, -10, 4, -2, 12, -14, 12, -8, 6, -6, 16, -20, 22, -14, 4, -4, 8, -12, 24, -18, 6, -8, 24, -28, 30, -22, 4, -2, 24, -30, 26, -22, 12, -8, 28, -34, 22, -16, 12, -8, 30, -42, 44, -30, 6, -4, 16, -28, 46, -34, 12, -20, 46, -46, 48, -36, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

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

N. J. A. Sloane, Families of Essentially Identical Sequences, Mar 24 2021 (Includes this sequence)

FORMULA

G.f.: -1 + (1 - x)*Sum_{k>=1} mu(k)*x^(k-1)/(1 - x^k)^2. - Ilya Gutkovskiy, Jan 29 2017

MATHEMATICA

Table[EulerPhi[n + 1] - EulerPhi[n], {n, 100}] (* Vincenzo Librandi, Sep 30 2013 *)

PROG

(MAGMA) [(EulerPhi(n+1) - EulerPhi(n)): n in [1..100]]; // Vincenzo Librandi, Sep 30 2013

(PARI) a(n) = eulerphi(n+1) - eulerphi(n); \\ Michel Marcus, Jan 29 2017

CROSSREFS

Cf. A000010, A001274.

Sequence in context: A063086 A077636 A215847 * A348044 A328400 A239676

Adjacent sequences:  A056997 A056998 A056999 * A057001 A057002 A057003

KEYWORD

sign

AUTHOR

N. J. A. Sloane, Sep 09 2000

STATUS

approved

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Last modified October 21 01:38 EDT 2021. Contains 348132 sequences. (Running on oeis4.)