A037083 Numbers k such that k!!! + 1 is prime (0 is included by convention).

0, 1, 2, 4, 5, 6, 7, 9, 10, 11, 17, 24, 29, 39, 40, 57, 58, 59, 91, 155, 175, 245, 359, 372, 597, 864, 977, 1077, 1327, 2076, 4798, 4975, 10830, 13453, 15472, 15948, 16116, 16681, 18037, 21725, 22326, 24753, 28565, 32659, 46487, 50649, 51393, 80069, 95493

Offset

1,3

Comments

n!!! = n*(n-3)*(n-6)*(n-9)*...

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

Table of n, a(n) for n=1..49.

Ray Ballinger, Status of Search for Multifactorial Primes

Ken Davis, Status of Search for Multifactorial Primes.

Ken Davis, Results for n!3+1.

Shyam Sunder Gupta, Fascinating Factorials, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 16, 411-442.

Index entries for sequences related to factorial numbers

Crossrefs

Cf. A007661 (triple factorials), A084438, A037082.

Sequence in context: A376956 A288866 A084437 * A188033 A187485 A039052

Adjacent sequences: A037080 A037081 A037082 * A037084 A037085 A037086

Keyword

nonn

Author

G. L. Honaker, Jr.

Extensions

More terms from Steven Harvey

Corrected and extended by Hugo Pfoertner, Jun 25 2003

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

Edited by N. J. A. Sloane, Jan 14 2008

Status

approved