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A295305 a(n) = tau(sigma(n)) - tau(n), where tau is the number of divisors (A000005) and sigma is the sum of divisors of n (A000203). 3

%I #9 Oct 26 2020 17:23:55

%S 0,0,1,-1,2,2,2,0,-1,2,4,0,2,4,4,-3,4,-2,4,2,2,5,6,4,-1,4,4,2,6,4,4,0,

%T 6,4,6,-5,2,8,4,4,6,4,4,6,2,8,8,-4,1,-2,8,0,6,8,8,8,6,8,10,4,2,8,2,-5,

%U 8,7,4,6,8,7,10,-4,2,4,0,6,8,8,8,-2,-2,8,10,0,8,8,12,10,10,0,6,10,4,11,12,6,4,0,6,-5,6,8,6,8,6

%N a(n) = tau(sigma(n)) - tau(n), where tau is the number of divisors (A000005) and sigma is the sum of divisors of n (A000203).

%H Antti Karttunen, <a href="/A295305/b295305.txt">Table of n, a(n) for n = 1..16384</a>

%F a(n) = A062068(n) - A000005(n).

%t Table[DivisorSigma[0,DivisorSigma[1,n]]-DivisorSigma[0,n],{n,110}] (* _Harvey P. Dale_, Oct 26 2020 *)

%o (PARI) A295305(n) = (numdiv(sigma(n)) - numdiv(n));

%Y Cf. A000005, A000203, A062068, A295306.

%Y Cf. A037197 (positions of zeros), A073803 (of positive terms), A073804 (of negative terms).

%K sign

%O 1,5

%A _Antti Karttunen_, Nov 21 2017

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Last modified April 25 01:06 EDT 2024. Contains 371964 sequences. (Running on oeis4.)