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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A252734 Smallest odd prime Q such that Q^2*2^prime(n)-1 is a prime number starting with n=2. 1
 3, 7, 3, 5, 3, 5, 83, 5, 7, 43, 11, 23, 3, 71, 47, 97, 109, 13, 19, 17, 53, 83, 97, 53, 43, 97, 5, 3, 43, 17, 19, 13, 307, 103, 293, 13, 11, 457, 113, 317, 67, 47, 311, 127, 281, 3, 97, 13, 127, 1223, 61, 307, 29 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 LINKS Pierre CAMI, Table of n, a(n) for n = 2..1800 EXAMPLE 3^2*2^3-1=71 prime so a(2)=3. 7^2*2^5-1=1567 prime so a(3)=7. MATHEMATICA Table[k=3; While[Not[PrimeQ[k^2*2^Prime[n]-1]], k=NextPrime[k]]; k, {n, 2, 100}] (* Vaclav Kotesovec, Dec 21 2014 *) PROG (PFGW & SCRIPT) SCRIPT DIM n, 1 DIM q OPENFILEOUT myf, a(n).txt LABEL loop1 SET n, n+1 SET q, 1 LABEL loop2 SET q, q+1 PRP p(q)^2*2^p(n)-1 IF ISPRP THEN GOTO a GOTO loop2 LABEL a WRITE myf, q GOTO loop1 CROSSREFS Cf. A252733. Sequence in context: A021968 A132821 A247217 * A101636 A193534 A096247 Adjacent sequences:  A252731 A252732 A252733 * A252735 A252736 A252737 KEYWORD nonn AUTHOR Pierre CAMI, Dec 21 2014 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.

Last modified July 25 01:31 EDT 2021. Contains 346273 sequences. (Running on oeis4.)