A133834 Numbers k such that primorial(k)^4 + 1 is prime.

0, 1, 2, 4, 23, 76, 339, 1282

Offset

1,3

Comments

Seven terms found and primes proved by PrimeForm ([N-1, Brillhart-Lehmer-Selfridge]). p(1282)#^4 + 1 has 18042 decimal digits. There are no more terms <= 2810.

a(9) > 5000. - Michael S. Branicky, Apr 13 2025

Links

Table of n, a(n) for n=1..8.

Example

As primorial(2)^4 + 1 = (3*2)^4 + 1 = 1297 is prime, 2 is a term.

Crossrefs

Cf. A002110, A092061.

Sequence in context: A349765 A018279 A307459 * A203103 A308164 A173352

Adjacent sequences: A133831 A133832 A133833 * A133835 A133836 A133837

Keyword

nonn,hard,more

Author

Rick L. Shepherd, Sep 26 2007

Extensions

a(1) = 0 inserted by Michael S. Branicky, Apr 13 2025

Status

approved