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a(n) = A001065(n) mod A000005(n).
1

%I #12 Sep 08 2022 08:45:45

%S 0,1,1,0,1,2,1,3,1,0,1,4,1,2,1,0,1,3,1,4,3,2,1,4,0,0,1,4,1,2,1,1,3,0,

%T 1,1,1,2,1,2,1,6,1,4,3,2,1,6,2,1,1,4,1,2,1,0,3,0,1,0,1,2,5,0,3,6,1,4,

%U 3,2,1,3,1,0,1,4,3,2,1,6,0,0,1,8,3,2,1,4,1,0,1,4,3,2,1,0,1,1,3,0,1,2,1,2,7

%N a(n) = A001065(n) mod A000005(n).

%C A054022(n) for n > 1 gives the numbers k such that a(k) = 1.

%H Antti Karttunen, <a href="/A160550/b160550.txt">Table of n, a(n) for n = 1..16384</a>

%t Table[Mod[DivisorSigma[1,n]-n,DivisorSigma[0,n]],{n,110}] (* _Harvey P. Dale_, Jun 22 2013 *)

%o (Magma) [ (SumOfDivisors(n)-n) mod NumberOfDivisors(n): n in [1..105] ]; // _Klaus Brockhaus_, May 21 2009

%o (PARI) A160550(n)=lift(Mod(sigma(n)-n,numdiv(n))); \\ _Michael B. Porter_, Oct 13 2009

%Y Cf. A000203, A000027, A000005, A054022, A001065, A003601, A140480.

%K easy,nonn

%O 1,6

%A _Ctibor O. Zizka_, May 19 2009

%E Extended and comment edited by _Klaus Brockhaus_, May 21 2009