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A363085
Sum of the refactorable unitary divisors of n.
3
1, 3, 1, 1, 1, 3, 1, 9, 10, 3, 1, 13, 1, 3, 1, 1, 1, 30, 1, 1, 1, 3, 1, 33, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 46, 1, 3, 1, 49, 1, 3, 1, 1, 10, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 65, 1, 3, 1, 73, 1, 3, 10, 1, 1, 3, 1, 1, 1, 3, 1, 90, 1, 3, 1, 1, 1, 3, 1, 81, 1, 3, 1, 97, 1, 3, 1, 97
OFFSET
1,2
FORMULA
a(n) = Sum_{d|n, tau(d)|d, gcd(d,n/d)=1} d.
MATHEMATICA
a[n_] := DivisorSum[n, # &, CoprimeQ[#, n/#] && Divisible[#, DivisorSigma[0, #]] &]; Array[a, 100]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, May 27 2023
STATUS
approved