

A160600


Numbers n such that 3*(2n)^(2n)+1 is prime.


4




OFFSET

1,2


COMMENTS

This corresponds to the numbers such that 3m^m+1 is prime, but these must all be even, m=2n, and therefore it is more natural to record the sequence of n=m/2.
Next term > 15000.  Matevz Markovic, Oct 09 2012


LINKS

Table of n, a(n) for n=1..6.


EXAMPLE

a(1) = 1, because 2^2*3+1 = 13 is the smallest prime of this form.
a(2) = 2, because 4^4*3+1 = 769 is the next smallest prime of this form. a(3) = 3, because 6^6*3+1 = 139969 is again a prime.


PROG

(PARI) for(i=1, 9999, ispseudoprime(i^i*3+1)&print1(i/2, ", "))


CROSSREFS

Cf. A160360 (3n^n+2 is prime), A121270 = primes among Sierpinski numbers A014566(n)=n^n+1; A216148 = A216147(A110932): primes 2n^n+1; A088790, A065798.
Sequence in context: A117702 A041343 A229349 * A325505 A319609 A140551
Adjacent sequences: A160597 A160598 A160599 * A160601 A160602 A160603


KEYWORD

hard,more,nonn


AUTHOR

M. F. Hasler, Jul 10 2009


STATUS

approved



