A384697 Primes of the form floor(2^k / 5).

3, 409, 6553, 1677721, 6871947673, 472236648286964521369, 7922816251426433759354395033, 2451992865385422173373355243440494693789982595493763481

Offset: 1

Author

Vincenzo Librandi, Jun 07 2025

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..15

Crossrefs

Cf. A383966 (corresponding k).

Programs

Magma

[ a: k in [0..500] | IsPrime(a) where a is 2^k div 5 ];

Mathematica

Select[Table[Quotient[(2^n), 5],{n,1,250}],PrimeQ]

Formula

a(n) = floor(2^A383966(n)/5).