A295301 a(n) = n - phi(sigma(n)), where phi = A000010 and sigma = A000203.

0, 0, 1, -2, 3, 2, 3, 0, -3, 4, 7, 0, 7, 6, 7, -14, 11, -6, 11, 8, 5, 10, 15, 8, -5, 14, 11, 4, 21, 6, 15, -4, 17, 16, 19, -36, 19, 22, 15, 16, 29, 10, 23, 20, 21, 22, 31, -12, 13, -10, 27, 10, 35, 22, 31, 24, 25, 34, 43, 12, 31, 30, 15, -62, 41, 18, 35, 32, 37, 22, 47, -24, 37, 38, 15, 28, 45, 30, 47, 20

Offset: 1

Author

Antti Karttunen, Nov 21 2017

Keywords

• sign

Links

• Antti Karttunen, Table of n, a(n) for n = 1..32768

Crossrefs

Cf. A000010, A000203, A062401, A295303.

Cf. A001229 (positions of zeros), A066694 (of negative terms).

Cf. also A295302, A295305.

Programs

GAP

a:=List([1..80],n->n-Phi(Sigma(n)));; Print(a); # Muniru A Asiru, Jan 02 2019

Magma

[n-EulerPhi(SumOfDivisors(n)):n in [1..100]]; // Marius A. Burtea, Jan 01 2019

Maple

with(numtheory): seq(n-phi(sigma(n)),n=1..80); # Muniru A Asiru, Jan 02 2019

Mathematica

Array[# - EulerPhi@ DivisorSigma[1, #] &, 80] (* Michael De Vlieger, Jan 01 2019 *)

PARI

A295301(n) = (n - eulerphi(sigma(n)));

Formula

a(n) = n - A062401(n).