A299642 Numbers k such that 2^k + 5*k is a prime.

1, 3, 7, 9, 15, 21, 33, 37, 61, 141, 159, 229, 345, 373, 511, 717, 2065, 2337, 15619, 22771, 22875, 23911, 29323, 53025

Offset

1,2

Comments

a(19) = 15619 corresponds to a probable prime. - Jon E. Schoenfield, Feb 28 2018

Links

Table of n, a(n) for n=1..24.

Maple

a:=n->`if`(isprime(2^n+5*n), n, NULL): seq(a(n), n=1..7000); # Muniru A Asiru, Mar 10 2018

Mathematica

Select[Range[7000], PrimeQ[2^# + 5 #] &]

Prog

(Magma) [n: n in [0..2000] |IsPrime(2^n+5*n)];
(PARI) isok(k) = isprime(2^k + 5*k); \\ Altug Alkan, Mar 03 2018

Crossrefs

Cf. A297663.

Sequence in context: A261871 A191131 A282572 * A128539 A192118 A282534

Adjacent sequences: A299639 A299640 A299641 * A299643 A299644 A299645

Keyword

nonn,more

Author

Vincenzo Librandi, Feb 28 2018

Extensions

a(19) from Jon E. Schoenfield, Feb 28 2018

a(20)-a(23) from Daniel Suteu, Mar 11 2018

a(24) from Michael S. Branicky, Mar 28 2023

Status

approved