cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A075071 n! divided by product of factorials of all proper divisors of n, as n runs through the values for which the result is an integer.

Original entry on oeis.org

1, 2, 6, 12, 120, 60, 5040, 840, 60480, 15120, 39916800, 2310, 6227020800, 8648640, 1816214400, 10810800, 355687428096000, 2042040, 121645100408832000, 116396280, 1689515283456000, 14079294028800, 25852016738884976640000
Offset: 1

Views

Author

Amarnath Murthy, Sep 09 2002

Keywords

Comments

n! divided by the product of factorials of all proper divisors of n is not always an integer; e.g., when n = 24 the quotient is 7436429/48. See A075422.

Examples

			a(12) = 12! / (2!*3!*4!*6!) = 2310.
		

Crossrefs

Cf. A075422.

Programs

  • Mathematica
    Select[Table[ n!/ Apply[ Times, Drop[ Divisors[n], -1]! ], {n, 1, 23}], IntegerQ]
    Select[Table[n!/Times@@(Most[Divisors[n]]!),{n,30}],IntegerQ] (* Harvey P. Dale, Aug 01 2020 *)

Extensions

Edited by Robert G. Wilson v, Sep 14 2002
First Mathematica program modified by Harvey P. Dale, Aug 01 2020