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A065395 Commutator of sigma and phi functions. 11
0, -1, 1, -3, 5, -1, 8, -1, 0, 1, 14, -5, 22, 4, 7, -15, 25, -12, 31, 3, 12, 6, 28, -1, 12, 16, 23, 4, 48, -9, 56, -5, 26, 13, 44, -44, 73, 23, 36, 7, 78, -4, 76, 18, 36, 12, 56, -29, 60, -18, 39, 18, 80, 7, 66, 28, 59, 32, 74, -17, 138, 40, 43, -63, 100, -6 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = sigma(phi(n)) - phi(sigma(n)) = A000203(A000010(n)) - A000010(A000203(n)).

EXAMPLE

n = 13: sigma(13) = 14, phi(14) = 6, phi(13) = 12, sigma(12) = 28, a(13) = 28-6 = 22.

MAPLE

with(numtheory); A065395:=n->sigma(phi(n))-phi(sigma(n)); seq(A065395(n), n=1..100); # Wesley Ivan Hurt, Dec 26 2013

MATHEMATICA

Table[DivisorSigma[1, EulerPhi[n]] - EulerPhi[DivisorSigma[1, n]], {n, 100}] (* T. D. Noe, Nov 04 2013 *)

PROG

(PARI) { for (n=1, 1000, a=sigma(eulerphi(n)) - eulerphi(sigma(n)); write("b065395.txt", n, " ", a) ) } \\ Harry J. Smith, Oct 18 2009

(MAGMA) [DivisorSigma(1, EulerPhi(n))-EulerPhi(DivisorSigma(1, n)): n in [1..70]]; // Bruno Berselli, Oct 20 2015

CROSSREFS

Cf. A000010, A000203, A033632.

Sequence in context: A318190 A289714 A242390 * A236631 A302800 A197326

Adjacent sequences:  A065392 A065393 A065394 * A065396 A065397 A065398

KEYWORD

sign

AUTHOR

Labos Elemer, Nov 05 2001

STATUS

approved

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Last modified September 18 09:56 EDT 2019. Contains 327169 sequences. (Running on oeis4.)