A093621 Smallest k>0 such that n!/k!+1 is prime.

1, 1, 1, 1, 2, 2, 4, 2, 2, 4, 3, 1, 5, 2, 3, 4, 2, 3, 5, 19, 10, 3, 5, 4, 5, 7, 5, 1, 6, 21, 2, 9, 15, 15, 13, 10, 27, 1, 4, 37, 14, 1, 4, 2, 34, 5, 8, 18, 24, 2, 13, 5, 11, 35, 48, 11, 7, 48, 27, 21, 30, 5, 43, 7, 4, 46, 13, 24, 16, 60, 12, 34, 5, 1, 38, 14, 28, 1, 10, 24, 50, 5, 3, 42, 40, 28

Offset

0,5

Comments

The results were computed using the PrimeFormGW (PFGW) primality-testing program. - Hugo Pfoertner, Nov 14 2019

Links

Table of n, a(n) for n=0..85.

Formula

a(A002981(n)) = 1.

Example

a(39) =37 because 39!/k!+1 is composite for all k=1..36; 39!/37!+1=39*38+1=1483 is prime.

Crossrefs

Cf. A093437 largest prime of the form n!/k!+1, A002981 n!+1 is prime, A093623 Smallest k>0 such that n!/k!-1 is prime.

Sequence in context: A367953 A212595 A087692 * A242734 A309709 A143230

Adjacent sequences: A093618 A093619 A093620 * A093622 A093623 A093624

Keyword

nonn

Author

Hugo Pfoertner, Apr 06 2004

Status

approved