A085895 Group the natural numbers such that the product of the n-th group is divisible by 2^n. (1), (2), (3,4), (5,6,7,8), (9,10,11,12,13,14),(15,16,17,18), ... Sequence contains the product of the terms of the groups.

1, 2, 12, 1680, 2162160, 73440, 96909120, 424097856000, 5339572260422400, 57407703889536000, 1573144097507348889600, 89247024757574635311360000, 131197375012291112448000, 6932022668773077815267328000

Offset

0,2

Links

Table of n, a(n) for n=0..13.

Formula

From Chayim Lowen, Jul 29 2015: (Start)

Product_{m=0..n} a(m) = (A085897(n+1)-1)! whence:

a(n) = (A085897(n+1)-1)!/a(n-1).

a(n) = (A085897(n+1)-1)!/(A085897(n)-1)!. (End)

Example

a(3) = 1680 = 5*6*7*8 = 2^3*(5*6*7) is divisible by 2^3=8. (In fact, it is divisible by 2^4, but 5*6*7 is not divisible by 8.)

Crossrefs

Cf. A085896, A085897, A085898.

Sequence in context: A111180 A235857 A085912 * A090904 A125295 A222065

Adjacent sequences: A085892 A085893 A085894 * A085896 A085897 A085898

Keyword

nonn

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jul 10 2003

Extensions

More terms from Ray Chandler, Sep 13 2003

Status

approved