A108062 Numbers k such that 2^(2k-1) + 2^k + 1 is prime.

1, 2, 3, 6, 10, 15, 79, 82, 142, 190, 499, 5071, 7350, 38646, 42619, 53347

Offset

1,2

Comments

Next term >= 10^4. - Jeppe Stig Nielsen, Mar 28 2014

Links

Table of n, a(n) for n=1..16.

Jacques Basaldua, All Fermat and Mersenne numbers are squarefree.

Formula

a(n) = A006599(n) + 1.

Mathematica

Do[ If[ PrimeQ[2^(2n - 1) + 2^n + 1], Print[n]], {n, 5500}] (* Robert G. Wilson v, Jun 03 2005 *)

Prog

(PARI) is(n)=ispseudoprime(2^(2*n-1)+2^n+1) \\ Charles R Greathouse IV, Jun 12 2017

Crossrefs

Cf. A006599, A138576.

Sequence in context: A048681 A375972 A051891 * A347117 A269403 A075623

Adjacent sequences: A108059 A108060 A108061 * A108063 A108064 A108065

Keyword

nonn,more

Author

Alexandre Wajnberg, Jun 02 2005

Extensions

a(1) and a(12) from Robert G. Wilson v, Jun 03 2005

a(13) from Jeppe Stig Nielsen, Mar 28 2014

a(14)-a(16) from Michael S. Branicky, Jan 02 2025

Status

approved