A359436 Primes p such that (4^p - 2^p + 1)/3 is prime.

3, 5, 7, 13, 29, 61, 383, 401, 1637, 1871, 36229, 44771, 44797, 75167

Offset

1,1

Comments

Terms > 1871 correspond to probable primes.

Links

Table of n, a(n) for n=1..14.

Example

3 is a term because 3 is prime and (4^3 - 2^3 + 1)/3 = 19 is also prime.

Prog

(PARI) isok(p)={isprime(p) && p>2 && ispseudoprime((4^p - 2^p + 1)/3)}
{ forprime(p=3, 2000, if(isok(p), print1(p, ", "))) } \\ Andrew Howroyd, Dec 31 2022

Crossrefs

Cf. A000978.

Sequence in context: A128547 A087383 A038928 * A225504 A089740 A191473

Adjacent sequences: A359433 A359434 A359435 * A359437 A359438 A359439

Keyword

nonn,more,hard

Author

Jorge Coveiro, Dec 31 2022

Status

approved