login
a(n) is Chowla function of n read modulo (number of proper divisors of n), a(1) = 0 by convention.
5

%I #10 Oct 27 2023 22:00:46

%S 0,0,0,0,0,2,0,0,1,1,0,0,0,0,2,2,0,0,0,1,1,1,0,0,1,0,0,2,0,6,0,0,2,1,

%T 0,6,0,0,1,0,0,4,0,4,2,1,0,3,1,2,2,0,0,2,1,0,1,1,0,8,0,0,0,2,0,0,0,2,

%U 2,3,0,1,0,0,3,3,0,5,0,6,3,1,0,7,1,0,2,0,0,0,2,0,1,1,0,1,0,2,1,4,0,1,0,0,2

%N a(n) is Chowla function of n read modulo (number of proper divisors of n), a(1) = 0 by convention.

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

%H Antti Karttunen, <a href="/A054015/b054015.txt">Table of n, a(n) for n = 1..16384</a>

%H <a href="/index/Su#sums_of_divisors">Index entries for sequences related to sums of divisors</a>

%F a(1) = 0; for n > 1, a(n) = A048050(n) mod A032741(n).

%p with(numtheory): [seq((sigma(i)-i-1) mod (tau(i)-1),i=2..120);#i>1

%o (PARI) A054015(n) = if(1==n,0,((sigma(n)-n-1) % (numdiv(n)-1))); \\ _Antti Karttunen_, Oct 20 2017

%Y Cf. A032741, A048050, A054013, A054014.

%K nonn

%O 1,6

%A _Asher Auel_, Jan 17 2000

%E Description clarified by _Antti Karttunen_, Oct 20 2017