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Chowla function of n read modulo n.
7

%I #11 Oct 27 2023 22:00:46

%S 0,0,0,2,0,5,0,6,3,7,0,3,0,9,8,14,0,2,0,1,10,13,0,11,5,15,12,27,0,11,

%T 0,30,14,19,12,18,0,21,16,9,0,11,0,39,32,25,0,27,7,42,20,45,0,11,16,7,

%U 22,31,0,47,0,33,40,62,18,11,0,57,26,3,0,50,0,39,48,63,18,11,0,25,39,43,0

%N Chowla function of n read modulo n.

%C Chowla's function (A048050) = sum of divisors of n except 1 and n.

%H Antti Karttunen, <a href="/A054013/b054013.txt">Table of n, a(n) for n = 1..16384</a>

%F a(n) = A048050(n) mod n

%p with(numtheory): [seq((sigma(i) - i - 1) mod i, i=2..100)];

%t Table[Mod[DivisorSigma[1,n]-n-1,n],{n,90}] (* _Harvey P. Dale_, Dec 01 2011 *)

%o (PARI) A054013(n) = ((sigma(n)-n-1) % n); \\ _Antti Karttunen_, Oct 30 2017

%Y Cf. A048050, A054014, A054015.

%K nonn

%O 1,4

%A _Asher Auel_, Jan 17 2000