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a(n) = sigma(n) mod phi(n).
8

%I #25 Feb 19 2024 10:33:32

%S 0,0,0,1,2,0,2,3,1,2,2,0,2,0,0,7,2,3,2,2,8,6,2,4,11,6,4,8,2,0,2,15,8,

%T 6,0,7,2,6,8,10,2,0,2,4,6,6,2,12,15,13,8,2,2,12,32,0,8,6,2,8,2,6,32,

%U 31,36,4,2,30,8,0,2,3,2,6,4,32,36,0,2,26,13,6,2

%N a(n) = sigma(n) mod phi(n).

%C If a(n)=0, then n is a balanced number (A020492).

%H Harry J. Smith, <a href="/A063514/b063514.txt">Table of n, a(n) for n = 1..2000</a>

%F a(p^2) = 2*p+1, for prime p>=5. - _Michel Marcus_, Apr 07 2020

%o (PARI) { for (n=1, 2000, write("b063514.txt", n, " ", sigma(n)%eulerphi(n)) ) } \\ _Harry J. Smith_, Aug 24 2009

%o (Magma) [SumOfDivisors(n) mod EulerPhi(n): n in [1..85]]; // _Bruno Berselli_, Jan 31 2013

%Y Cf. A000010, A000203, A020492, A023897.

%K nonn

%O 1,5

%A _Labos Elemer_, Jul 31 2001