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

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..640

Reinhard Zumkeller, Products of largest prime factors of numbers <= n.

Formula

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

Mathematica

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

Prog

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

Crossrefs

Cf. A000203, A104350, A104352, A062569.

Sequence in context: A026557 A124052 A215640 * A001860 A199035 A101459

Adjacent sequences: A104350 A104351 A104352 * A104354 A104355 A104356

Keyword

nonn

Author

Reinhard Zumkeller, Mar 06 2005

Extensions

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

Status

approved