A212282 Minimal m >= 1 such that n!/m-1 is prime.

1, 1, 2, 1, 1, 4, 2, 4, 5, 1, 10, 1, 4, 3, 6, 4, 8, 6, 9, 25, 4, 28, 12, 11, 9, 10, 3, 1, 2, 1, 1, 3, 34, 5, 9, 1, 35, 24, 2, 5, 3, 24, 16, 7, 5, 32, 23, 6, 13, 13, 16, 7, 6, 20, 7, 31, 6, 94, 22, 26, 78, 9, 21, 8, 15, 11, 88, 11, 7, 58, 64, 56, 16

Offset: 3

Author

Vladimir Shevelev, Feb 14 2013

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 3..1002

Crossrefs

Cf. A212281.

Programs

Mathematica

a[n_] := Block[{f = n!, j=1}, While[! PrimeQ[Floor[f/j]-1], j++]; j]; v = a /@ Range[3,75] (* Giovanni Resta, Feb 14 2013 *)

Extensions

a(12)-a(75) from Giovanni Resta, Feb 14 2013