A050522 Primes of form 5*2^n-1.

19, 79, 1279, 5119, 20479, 81919, 1310719, 21474836479, 1407374883553279, 90071992547409919, 23611832414348226068479, 1784059615882449851322857461811868920478433279

Offset: 1

Author

N. J. A. Sloane, Dec 29 1999

Keywords

• nonn
• nice

Links

• Heiko Harborth, On h-perfect numbers, Annales Mathematicae et Informaticae, 41 (2013) pp. 57-62.
• Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

Crossrefs

See A001770 for more terms.

Programs

Mathematica

Select[Table[5*2^n-1,{n,0,150}],PrimeQ] (* Jean-François Alcover, Mar 21 2011 *)

Formula

a(n) = 5*2^A001770(n) - 1. - Max Alekseyev, Feb 20 2024