OFFSET
1,2
COMMENTS
Numbers k such that k*prime(k)+k-1 is prime.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(7) = 15 is a term because A083723(15) = 15*47+14 = 719 is prime.
MAPLE
select(n -> isprime(n*ithprime(n)+n-1), [$1..1000]);
MATHEMATICA
Select[Range[200], PrimeQ[(Prime[#] + 1)*# - 1] &] (* Amiram Eldar, Dec 19 2021 *)
PROG
(PARI) isok(k) = isprime(k*prime(k)+k-1); \\ Michel Marcus, Dec 19 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Dec 19 2021
STATUS
approved