A295301 - OEIS

%I #22 Sep 08 2022 08:46:20

%S 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,

%T 21,6,15,-4,17,16,19,-36,19,22,15,16,29,10,23,20,21,22,31,-12,13,-10,

%U 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

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

%H Antti Karttunen, <a href="/A295301/b295301.txt">Table of n, a(n) for n = 1..32768</a>

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

%p with(numtheory): seq(n-phi(sigma(n)),n=1..80); # _Muniru A Asiru_, Jan 02 2019

%t Array[# - EulerPhi@ DivisorSigma[1, #] &, 80] (* _Michael De Vlieger_, Jan 01 2019 *)

%o (PARI) A295301(n) = (n - eulerphi(sigma(n)));

%o (Magma) [n-EulerPhi(SumOfDivisors(n)):n in [1..100]]; // _Marius A. Burtea_, Jan 01 2019

%o (GAP) a:=List([1..80],n->n-Phi(Sigma(n)));; Print(a); # _Muniru A Asiru_, Jan 02 2019

%Y Cf. A000010, A000203, A062401, A295303.

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

%Y Cf. also A295302, A295305.

%K sign

%O 1,4

%A _Antti Karttunen_, Nov 21 2017