A172156 Primes in the chain of repeated application of x->2*x+3, starting at x=2.

7, 17, 37, 157, 317, 1277, 2557, 20477, 655357, 5242877, 671088637, 2684354557, 5368709117, 343597383677, 23058430092136939517, 23611832414348226068477, 48357032784585166988247037, 830767497365572420564879412675215357

Offset: 1

Author

Vincenzo Librandi, Jan 27 2010

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..37

Crossrefs

Cf. A154117. [Klaus Brockhaus, Feb 28 2010]

Programs

Magma

x:=2; a:=[n eq 1 select 2*x+3 else 2*Self(n-1)+3: n in [1..120]]; [a[i]: i in [1..#a] | IsPrime(a[i])]; // Bruno Berselli, May 14 2013

Mathematica

Rest[Select[NestList[2#+3&,2,500],PrimeQ]] (* Harvey P. Dale, Nov 17 2012 *)