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Topic: What is the next number in this series?
Replies: 33   Last Post: Feb 20, 2012 12:54 AM

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 quasi Posts: 9,080 Registered: 7/15/05
Re: What is the next number in this series?
Posted: Feb 9, 2012 11:07 AM

On Thu, 09 Feb 2012 16:48:16 +0100, AP

>On Wed, 8 Feb 2012 20:47:16 -0800 (PST), Slick itler
><toseriously@gmail.com> wrote:
>

>>1,2,8, ...
> why not 64 ?
>because 2^((n-1)n/2)
>is 1 for n=1
>is 2 for n=2
>is 8 for n=3
>is 64 for n=4

Sure, that works.

An OEIS search also yields this one

(2n)!!

as well as more than 2000 other sequences matching the
initial terms 1,2,8.

But in fact, for any value of a_4, the sequence

1,2,8,a_4

can be matched by an appropriately chosen expression for a_n.

quasi

Date Subject Author
2/8/12 Slick itler
2/8/12 quasi
2/9/12 donstockbauer@hotmail.com
2/9/12 Bill Taylor
2/9/12 Tim Little
2/9/12 Jussi Piitulainen
2/9/12 noname
2/9/12 David R Tribble
2/10/12 Helmut Richter
2/9/12 Jim Burns
2/9/12 Jim Burns
2/9/12 quasi
2/9/12 Michael Stemper
2/11/12 Bill Taylor
2/11/12 quasi
2/14/12 Bill Taylor
2/19/12 Risto Kauppila
2/19/12 Risto Kauppila
2/9/12 Jose Carlos Santos
2/9/12 David C. Ullrich
2/9/12 AP
2/9/12 Butch Malahide
2/9/12 quasi
2/9/12 Jussi Piitulainen
2/9/12 AP
2/9/12 J. Antonio Perez M.
2/9/12 Dan Christensen
2/9/12 Usher73
2/10/12 noname
2/9/12 K_h
2/10/12 noname
2/10/12 G. A. Edgar
2/11/12 Pfsszxt@aol.com