A227446 Numbers k such that 7*2^(2*k) - 5*2^k + 1 is prime.

0, 1, 3, 13, 39, 539, 2631, 4283, 13595

Offset

1,3

Comments

a(9) > 10000. - Jinyuan Wang, Feb 12 2019

a(10) > 10^5. - Michael S. Branicky, Nov 26 2024

Links

Table of n, a(n) for n=1..9.

Eric L. F. Roettger, A Cubic Extension of the Lucas Functions, Ph. D. Dissertation, Dept. Math. and Statistics, Univ. Calgary, 2009 (see page 196).

Maple

select(isprime, [seq(7*2^(2*n)-5*2^n+1, n=0..1000)]); # Jinyuan Wang, Feb 12 2019

Mathematica

Select[Range[0, 3000], PrimeQ[7 2^(2 #) - 5 2^# + 1]&]

Prog

(PARI) for(n=0, 10^6, if(ispseudoprime(7*2^(2*n)-5*2^n+1), print1(n, ", "))); \\ Joerg Arndt, Jul 14 2013

Crossrefs

Cf. A058593.

Sequence in context: A167910 A147042 A018492 * A059020 A290720 A289654

Adjacent sequences: A227443 A227444 A227445 * A227447 A227448 A227449

Keyword

nonn,more,changed

Author

Vincenzo Librandi, Jul 14 2013

Extensions

a(8) from Jinyuan Wang, Feb 12 2019

a(9) from Michael S. Branicky, Apr 23 2023

Status

approved