OFFSET
1,3
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
EXAMPLE
a(5) = 6 because sopf(5) = 5, and the sum of the 2 odd divisors of 5, {1, 5}, is 6.
MATHEMATICA
Table[Total[Select[Divisors[Plus@@First[Transpose[FactorInteger[n]]]], OddQ[#]&]], {n, 100}]
sopf[n_] := Total[FactorInteger[n][[;; , 1]]]; oddsigma[n_] := DivisorSigma[1, n/2^IntegerExponent[n, 2]]; a[1] = 0; a[n_] := oddsigma[sopf[n]]; Array[a, 100] (* Amiram Eldar, May 18 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Jul 29 2011
STATUS
approved