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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. 3
1, 2, 12, 1680, 2162160, 73440, 96909120, 424097856000, 5339572260422400, 57407703889536000, 1573144097507348889600, 89247024757574635311360000, 131197375012291112448000, 6932022668773077815267328000 (list; graph; refs; listen; history; text; internal format)
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

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Last modified May 11 13:41 EDT 2021. Contains 343791 sequences. (Running on oeis4.)