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

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..1000

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

Formula

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

Mathematica

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

Prog

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

Crossrefs

Cf. A000005, A104350, A104353, A027423.

Sequence in context: A052823 A063516 A306315 * A370584 A133488 A351016

Adjacent sequences: A104349 A104350 A104351 * A104353 A104354 A104355

Keyword

nonn

Author

Reinhard Zumkeller, Mar 06 2005

Extensions

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

Status

approved