A104352 Number of divisors of A104350(n).

1, 2, 4, 6, 12, 18, 36, 48, 64, 96, 192, 240, 480, 720, 960, 1200, 2400, 2880, 5760, 7200, 9600, 14400, 28800, 33600, 40320, 60480, 69120, 86400, 172800, 201600, 403200, 483840, 645120, 967680, 1161216, 1306368, 2612736, 3919104, 5225472, 5971968

Offset: 1

Author

Reinhard Zumkeller, Mar 06 2005

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..1000
• Reinhard Zumkeller, Products of largest prime factors of numbers <= n.

Crossrefs

Cf. A000005, A104350, A104353, A027423.

Programs

Mathematica

DivisorSigma[0, FoldList[Times, Array[FactorInteger[#][[-1, 1]] &, 50]]] (* Amiram Eldar, Apr 08 2024 *)

PARI

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

Formula

a(n) = A000005(A104350(n)).

Extensions

Offset changed to 1 and a(1) prepended by Amiram Eldar, Apr 08 2024