A135937 a(1)=1; for n>=2, a(n) = Product_{d|a(n-1)} (d+1), where the product is over all positive divisors d of a(n-1).

1, 2, 6, 168, 6623019333730800000

Offset

1,2

Comments

The next term is a lot bigger than 70000! and is too large to include. - Stefan Steinerberger, Dec 31 2007

Links

Table of n, a(n) for n=1..5.

Example

The positive divisors of a(3)=6 are 1,2,3,6. So a(4) = (1+1)*(2+1)*(3+1)*(6+1) = 2*3*4*7 = 168.

Mathematica

a = {1}; Do[AppendTo[a, Times @@ (Divisors[a[[ -1]]] + 1)], {4}]; a (* Stefan Steinerberger, Dec 31 2007 *)

Crossrefs

Cf. A135938.

Sequence in context: A329980 A199482 A168649 * A182523 A137532 A072116

Adjacent sequences: A135934 A135935 A135936 * A135938 A135939 A135940

Keyword

nonn

Author

Leroy Quet, Dec 07 2007

Extensions

a(5) from Stefan Steinerberger, Dec 31 2007

Status

approved