A050808 Numbers k such that floor(exp(k)) is prime.

1, 2, 18, 50, 127, 141, 267, 310, 2290, 4487, 5391, 14025

Offset: 1

Author

Patrick De Geest, Oct 15 1999

Keywords

• nonn
• hard
• more

Links

• Eric Weisstein's World of Mathematics, e-Prime

Crossrefs

Cf. A050809 (the actual primes), A000149, A040016, A037028, A000227, A004791, A059791, A059792.

Programs

Mathematica

Do[ If[ PrimeQ[ Floor[ \[ExponentialE]^n] ], Print[n] ], {n, 0, 4750} ]
Select[Range[15000],PrimeQ[Floor[Exp[#]]]&] (* Harvey P. Dale, Oct 16 2012 *)

PARI

is(n)=ispseudoprime(exp(n)\1) \\ Charles R Greathouse IV, Jan 03 2014

Extensions

Corrected by Naohiro Nomoto, Feb 22 2001

More terms from Vladeta Jovovic, Feb 24 2001

More terms from Robert G. Wilson v, May 09 2001

a(11) = 5391 from Eric W. Weisstein, May 01 2006

a(12) from Donovan Johnson, Feb 04 2008