# [seqfan] RE : Re: Rank of a prime (Collatz/Syracuse)

Eric Angelini Eric.Angelini at kntv.be
Sun Feb 1 09:10:55 CET 2009

```> 2,3,4,7,5,31,8,55,4,33,6,30,32,1,4,20,9,113,56,16,28,4,4,27,2,21,224,103,34,14,7,163,2,10,11,76,31,114,22
> Number of iterations to repeat a term.

... Thanks to all for the nice computations (Jacques, Edwin, Robert G., Maximilian, etc.)
Best,
E.

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De: seqfan-bounces at list.seqfan.eu de la part de Robert G. Wilson, v
Date: dim. 01/02/2009 06:44
À: Sequence Fanatics Discussion list
Objet : [seqfan] Re: Rank of a prime (Collatz/Syracuse)

Edwin,

PrimePi[222312455509]=8862793537.

I use Mathematica and this one took me just 1.451 seconds.
Mathematica runs out of
its ability for the initial integer of 40.

Bob.

Edwin Clark wrote:

>On Sun, 1 Feb 2009, Jacques Tramu wrote:
>
>
>
>>So  the question is :
>>does any sequence terminates in "1"  or with the" 15 23 9 22 15 loop" ?
>>or 25 - ea(25)  is 25 33 25
>>
>>
>
>
>
>The first number I had trouble with was 18. The problem there is
>eventually it gets to the prime 222312455509 and I have difficulty
>figuring out pi(222312455509).
>
>
>
>
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