login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A078681 Start with n; iterate the process x -> ceiling(3x/2) until reach a prime. Sequence gives number of steps to reach a prime or 0 if no prime is ever reached. 1
1, 1, 1, 53, 5, 52, 1, 4, 51, 2, 1, 3, 39, 50, 1, 162, 3, 2, 1, 38, 49, 4, 2, 161, 50, 2, 1, 52, 4, 37, 1, 48, 3, 13, 1, 160, 9, 49, 1, 8, 42, 51, 18, 3, 36, 8, 1, 47, 3, 2, 12, 35, 27, 159, 1, 8, 48, 2, 1, 7, 4, 41, 50, 16, 17, 2, 1, 35, 7, 13, 1, 46, 11, 2, 1, 3, 11, 34, 2, 26, 158, 7, 6, 7 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..84.

PROG

(PARI) a(n)=if(n<0, 0, s=n; c=1; while(isprime(ceil(3*s/2))==0, s=ceil(3*s/2); c++); c)

CROSSREFS

Cf. A050412.

Sequence in context: A198776 A051320 A232126 * A143294 A143428 A143385

Adjacent sequences:  A078678 A078679 A078680 * A078682 A078683 A078684

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Dec 17 2002

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 4 15:36 EST 2021. Contains 349526 sequences. (Running on oeis4.)