A065546 a(n) is smallest prime > 2*a(n-1), a(1) = 13.

13, 29, 59, 127, 257, 521, 1049, 2099, 4201, 8419, 16843, 33703, 67409, 134837, 269683, 539389, 1078787, 2157587, 4315183, 8630387, 17260781, 34521589, 69043189, 138086407, 276172823, 552345671, 1104691373, 2209382761

Offset: 1

Author

Robert G. Wilson v, Nov 28 2001

Keywords

• nonn

Links

• Harry J. Smith, Table of n, a(n) for n = 1..200

Programs

Mathematica

NextPrim[n_Integer] := Block[ {k = n + 1}, While[ !PrimeQ[k], k++ ]; Return[k]]; a[1] = 13; a[n_] := NextPrim[ 2*a[n - 1]]; Table[ a[n], {n, 1, 35} ]
NestList[NextPrime[2#]&,13,30] (* Harvey P. Dale, Feb 25 2015 *)

PARI

{ for (n=1, 200, if (n>1, a=nextprime(2*a), a=13); write("b065546.txt", n, " ", a) ) } \\ Harry J. Smith, Oct 21 2009