A120621 Least positive k such that !n + k is prime, where !n is left factorial.

2, 1, 1, 1, 1, 3, 3, 3, 9, 3, 7, 9, 7, 13, 49, 27, 9, 37, 19, 33, 7, 93, 103, 9, 73, 27, 13, 27, 165, 49, 39, 93, 97, 27, 37, 39, 135, 7, 193, 249, 39, 103, 13, 33, 213, 129, 33, 13, 39, 115, 187, 19, 7, 387, 19, 489, 303, 63, 33, 235, 297, 495, 657, 465, 235, 193, 369, 129

Offset

0,1

Links

Amiram Eldar, Table of n, a(n) for n = 0..1000

Mathematica

a[n_] := Module[{k = 1, lf = Sum[i!, {i, 0, n - 1}]}, While[!PrimeQ[lf + k], k++]; k]; Array[a, 100, 0] (* Amiram Eldar, Dec 24 2019 *)

Crossrefs

Cf. A003422, A033932 (with n! instead of !n).

Sequence in context: A322494 A258445 A129179 * A201080 A039754 A213919

Adjacent sequences: A120618 A120619 A120620 * A120622 A120623 A120624

Keyword

easy,nonn

Author

Jason Earls, Aug 17 2006

Status

approved