OFFSET
1,3
COMMENTS
This sequence provides "simplest" examples of large primes of the form x^2+1, cf. A174246.
EXAMPLE
a(1)=0 since nextprime(2^0)=2 and 4*2^2+1 = 17 is prime.
MATHEMATICA
fQ[n_] := PrimeQ[ 4NextPrime[2^n]^2 + 1]; Select[ Range@ 3000, fQ] (* Robert G. Wilson v, Dec 27 2014 *)
PROG
(PARI) for(n=0, 9e9, ispseudoprime(4*nextprime(2^n)^2+1)&&print1(n", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Oct 12 2014
EXTENSIONS
a(13) and a(14) from Robert G. Wilson v, Dec 27 2014
STATUS
approved