A104353 Sum of divisors of A104350(n).

1, 3, 12, 28, 168, 546, 4368, 9360, 28800, 148800, 1785600, 5401440, 75620160, 538793640, 2711348640, 5603453856, 100862169408, 303420079872, 6068401597440, 30380907997440, 213199354368000, 2362959510912000, 56711028261888000, 170288884313856000

Offset: 1

Author

Reinhard Zumkeller, Mar 06 2005

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..640
• Reinhard Zumkeller, Products of largest prime factors of numbers <= n.

Crossrefs

Cf. A000203, A104350, A104352, A062569.

Programs

Mathematica

DivisorSigma[1, FoldList[Times, Array[FactorInteger[#][[-1, 1]] &, 30]]] (* Amiram Eldar, Apr 08 2024 *)

PARI

gpf(n) = {my(p = factor(n)[, 1]); p[#p];}
a(n) = sigma(prod(k = 2, n, gpf(k))); \\ Amiram Eldar, Apr 08 2024

Formula

a(n) = A000203(A104350(n)).

Extensions

a(14), a(21) corrected by Georg Fischer, Feb 28 2023