A114778 Cumulative product of triple factorial A007661.

1, 1, 2, 6, 24, 240, 4320, 120960, 9676800, 1567641600, 438939648000, 386266890240000, 750902834626560000, 2733286318040678400000, 33674087438261157888000000, 981936389699695364014080000000

Offset

0,3

Comments

This is the product analog of what for sums is A114347.

Links

Table of n, a(n) for n=0..15.

Eric Weisstein's World of Mathematics, Multifactorial.

Formula

a(n) = Product_{j=0..n} j!!!. a(n) = Product_{j=0..n} A007661(j). a(n) = n!!! * a(n-1) where a(0) = 1, a(1) = 1 and n >= 2. a(n) = n*(n-3)!!! * a(n-1) where a(0) = 1, a(1) = 1, a(2) = 2 and n >= 3.

Example

a(10) = 1!!! * 2!!! * 3!!! * 4!!! * 5!!! * 6!!! * 7!!! * 8!!! * 9!!! * 10!!!
= 1 * 2 * 3 * 4 * 10 * 18 * 28 * 80 * 162 * 280 = 438939648000 = 2^15 * 3^7 * 5^3 * 7^2.

Crossrefs

Cf. A006882, A000178, A114347.

Sequence in context: A052632 A052692 A052723 * A292751 A274098 A324141

Adjacent sequences: A114775 A114776 A114777 * A114779 A114780 A114781

Keyword

easy,nonn

Author

Jonathan Vos Post, Feb 18 2006

Status

approved