A363085 Sum of the refactorable unitary divisors of n.

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

Author

Wesley Ivan Hurt, May 27 2023

Keywords

• nonn
• easy

Crossrefs

Cf. A034444, A336041, A363298.

Programs

Mathematica

a[n_] := DivisorSum[n, # &, CoprimeQ[#, n/#] && Divisible[#, DivisorSigma[0, #]] &]; Array[a, 100]

Formula

a(n) = Sum_{d|n, tau(d)|d, gcd(d,n/d)=1} d.