A085148 Numbers k such that k!!!!! + 1 is prime.

0, 1, 2, 4, 6, 9, 11, 13, 15, 17, 23, 26, 31, 32, 35, 36, 49, 52, 89, 92, 106, 120, 141, 149, 173, 201, 280, 289, 353, 455, 483, 499, 543, 811, 866, 1010, 1126, 1557, 2358, 2411, 2435, 2485, 2491, 2772, 2851, 2937, 2996, 3642, 3777, 4123, 4642, 5566, 6416, 9202, 9382

Offset: 1

Author

Hugo Pfoertner, Jun 23 2003

Keywords

• hard
• nonn

Comments

The search for multifactorial primes started by Ray Ballinger is now continued by a team of volunteers on the website of Ken Davis (see link).

Links

• Robert Price, Table of n, a(n) for n = 1..64
• Ken Davis, Status of Search for Multifactorial Primes.
• Ken Davis, Results for n!5+1.

Crossrefs

Cf. A085157 (quintuple factorials), A085149.

Extensions

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 03 2008

a(56)-a(64), with a(62)-(64) from the Ken Davis link, added to b-file by Robert Price, Sep 23 2012