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A093520

Numbers n such that there exists no k with 0 < k < n for which n!/k + 1 is a prime.

1, 18, 51, 53, 84, 95, 100, 104, 106, 143, 178, 180, 181, 188, 202, 203, 211, 214, 217, 222, 227, 232, 237, 239, 244, 250, 258, 272, 281, 284, 300, 303, 313, 315, 317, 323, 326, 342, 358, 364, 370, 374, 386, 387, 396, 401, 409, 413, 422, 423, 429, 438, 440

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OFFSET

1,2

COMMENTS

Essentially the same as A092068. - R. J. Mathar, Sep 05 2008

LINKS

Table of n, a(n) for n=1..53.

MATHEMATICA

f[n_] := Block[{k = 1}, While[ !PrimeQ[n!/k + 1], k++ ]; If[k < n, n!/k + 1, 0]]; Do[ If[ f[n] == 0, Print[n]], {n, 440}]

Join[{1}, Select[Range[500], NoneTrue[#!/Range[#]+1, PrimeQ]&]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 14 2018 *)

CROSSREFS

Cf. A092969.