A104089 Largest prime <= 4^n.

3, 13, 61, 251, 1021, 4093, 16381, 65521, 262139, 1048573, 4194301, 16777213, 67108859, 268435399, 1073741789, 4294967291, 17179869143, 68719476731, 274877906899, 1099511627689, 4398046511093, 17592186044399, 70368744177643

Offset: 1

Author

Cino Hilliard, Mar 03 2005

Keywords

• easy
• nonn

Crossrefs

Cf. A014234, A104082, A104088, A104090-A104094, A003618, A104096.

Cf. A000040, A000302, A007917.

Programs

Mathematica

NextPrime[4^Range[30], -1] (* Paolo Xausa, Oct 28 2024 *)

PARI

g(n,b) = for(x=0,n,print1(precprime(b^x)","))

Formula

a(n) = A007917(A000302(n)). - Paolo Xausa, Oct 28 2024