A211418 a(n) = n!*(floor(n/30))!/((floor(n/2))!*(floor(n/3))!*(floor(n/5))!).

1, 1, 2, 6, 12, 60, 60, 420, 840, 2520, 2520, 27720, 13860, 180180, 360360, 360360, 720720, 12252240, 4084080, 77597520, 38798760, 116396280, 232792560, 5354228880, 1338557220, 6692786100, 13385572200, 40156716600, 80313433200

Offset: 0

Author

Peter Bala, Apr 11 2012

Keywords

• nonn
• easy

Comments

For positive real r the ratio of factorials floor((30*r*n))! * (floor(r*n))!/((floor(15*r*n))!*(floor(10*r*n))!*(floor(6*r*n))!) is an integer. The present sequence is the case r = 1/30. The case r = 1 is A211417.

Links

• Carauleanu Marc, Table of n, a(n) for n = 0..424
• P. Bala, Proof of the integrality of A211417 and A211418

Crossrefs

Cf. A211417.

Programs

PARI

a(n) = n!*(floor(n/30))!/((floor(n/2))!*(floor(n/3))!*(floor(n/5))!);
vector(50, n, a(n-1)) \\ Altug Alkan, Oct 02 2015