A363091 Sum of the divisor complements of the refactorable unitary divisors of n.

1, 3, 3, 4, 5, 9, 7, 9, 10, 15, 11, 13, 13, 21, 15, 16, 17, 30, 19, 20, 21, 33, 23, 28, 25, 39, 27, 28, 29, 45, 31, 32, 33, 51, 35, 41, 37, 57, 39, 46, 41, 63, 43, 44, 50, 69, 47, 48, 49, 75, 51, 52, 53, 81, 55, 64, 57, 87, 59, 66, 61, 93, 70, 64, 65, 99, 67, 68, 69, 105, 71

Offset

1,2

Links

Table of n, a(n) for n=1..71.

Formula

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

Mathematica

a[n_] := n*DivisorSum[n, 1/# &, CoprimeQ[#, n/#] && Divisible[#, DivisorSigma[0, #]] &]; Array[a, 100]

Crossrefs

Cf. A034444, A336041, A363085, A363298.

Sequence in context: A239483 A104806 A241442 * A043551 A162888 A337402

Adjacent sequences: A363088 A363089 A363090 * A363092 A363093 A363094

Keyword

nonn,easy

Author

Wesley Ivan Hurt, May 27 2023

Status

approved