A061765 a(n) = usigma(sigma(n)), where usigma(n) is the sum of unitary divisors of n (A034448) and sigma(n) is the sum of the divisors (A000203).

1, 4, 5, 8, 12, 20, 9, 24, 14, 30, 20, 40, 24, 36, 36, 32, 30, 56, 30, 96, 33, 50, 36, 120, 32, 96, 54, 72, 72, 90, 33, 80, 68, 84, 68, 112, 60, 120, 72, 180, 96, 132, 60, 160, 168, 90, 68, 160, 80, 128, 90, 150, 84, 216, 90, 216, 102, 180, 120, 288

Offset: 1

Author

N. J. A. Sloane, Oct 30 2001

Keywords

• nonn

Links

• Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000203, A034448.

Programs

Mathematica

a[n_] := Times @@ (1 + Power @@@ FactorInteger[DivisorSigma[1, n]]); a[1] = 1; Array[a, 100] (* Amiram Eldar, Aug 26 2022 *)

Formula

a(n) = A034448(A000203(n)). - Amiram Eldar, Aug 26 2022