OFFSET
1,2
LINKS
Jianing Song, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = (A048184(n)-1)/2.
EXAMPLE
9 is a term since 9 = 3^2 and that 2*9+1 = 19 is prime.
PROG
(PARI) is(n) = (n==1) || (isprimepower(n) && isprime(2*n+1))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jianing Song, Aug 13 2023
STATUS
approved