OFFSET

1,1

COMMENTS

a(8) has 504 digits and is too large to be included.

EXAMPLE

7 is a member of the sequence because 7 is a prime and 5^1 + 2*1 = 7.

29 is a member of the sequence because 29 is a prime and 5^2 + 2*2 = 29.

131 is a member of the sequence because 131 is a prime and 5^3 + 2*3 = 131.

MAPLE

a:=k->`if`(isprime(5^k+2*k), 5^k+2*k, NULL): seq(a(k), k=1..1500);

MATHEMATICA

Select[Table[5^k+2k, {k, 80}], PrimeQ] (* Harvey P. Dale, Jul 11 2021 *)

PROG

(GAP) Filtered(List([1..700], k ->5^k+2*k), IsPrime);

CROSSREFS

KEYWORD

nonn

AUTHOR

Muniru A Asiru, Apr 18 2018

STATUS

approved