A196940 Primes of the form 15*2^k - 1.

29, 59, 239, 479, 15359, 245759, 1966079, 32212254719, 32985348833279, 141670994486089356410879, 18133887294219437620592639, 72535549176877750482370559, 1246151246048358630847319119012823039, 638029437976759618993827388934565396479, 669022355955918694246071548179450845179412479

Offset: 1

Author

Brad Clardy, Oct 07 2011

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..28

Crossrefs

Primes in A196305.

Cf. A002237 (k such that 15*2^k-1 is prime).

Programs

Magma

[a: n in [1..130] | IsPrime(a) where a is 15*2^n-1]; // Vincenzo Librandi, Feb 23 2014

Mathematica

Select[Table[15 2^n - 1, {n, 1, 300}], PrimeQ] (* Vincenzo Librandi, Feb 23 2014 *)

PARI

for(n=1,1e3,if(ispseudoprime(t=15<Charles R Greathouse IV, Oct 08 2011

Formula

a(n) = A196305(A002237(n)). - Elmo R. Oliveira, Feb 23 2025