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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 (list; graph; refs; listen; history; text; internal format)
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..23.

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

STATUS

approved

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Last modified September 30 05:03 EDT 2020. Contains 337435 sequences. (Running on oeis4.)