A193350 Sum of even divisors of tau(n).
0, 2, 2, 0, 2, 6, 2, 6, 0, 6, 2, 8, 2, 6, 6, 0, 2, 8, 2, 8, 6, 6, 2, 14, 0, 6, 6, 8, 2, 14, 2, 8, 6, 6, 6, 0, 2, 6, 6, 14, 2, 14, 2, 8, 8, 6, 2, 12, 0, 8, 6, 8, 2, 14, 6, 14, 6, 6, 2, 24, 2, 6, 8, 0, 6, 14, 2, 8, 6, 14, 2, 24, 2, 6, 8, 8, 6, 14, 2, 12, 0, 6, 2, 24, 6, 6, 6, 14, 2, 24, 6, 8, 6, 6, 6, 24, 2, 8, 8, 0
Offset: 1
Keywords
Examples
a(24) = 14 because tau(24) = 8 and the sum of the 3 even divisors {2, 4, 8} is 14.
Links
- Antti Karttunen, Table of n, a(n) for n = 1..10000
Programs
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Mathematica
Table[Total[Select[Divisors[DivisorSigma[0,n]], EvenQ[ # ]&]], {n, 74}] -
PARI
a(n)=sumdiv(sigma(n,0),d,(1-d%2)*d);
Formula
Extensions
Data section extended to 100 terms by Antti Karttunen, May 28 2017