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A299642
Numbers k such that 2^k + 5*k is a prime.
2
1, 3, 7, 9, 15, 21, 33, 37, 61, 141, 159, 229, 345, 373, 511, 717, 2065, 2337, 15619, 22771, 22875, 23911, 29323, 53025, 106363, 127077
OFFSET
1,2
COMMENTS
a(19) = 15619 corresponds to a probable prime. - Jon E. Schoenfield, Feb 28 2018
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
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
a(25)-a(26) from Michael S. Branicky, Jun 23 2024
STATUS
approved