A270838 Largest value k < p-2 such that k! mod p = 1 with p = prime(n).

1, 1, 1, 1, 11, 1, 11, 10, 15, 1, 1, 1, 1, 37, 29, 52, 48, 35, 55, 1, 46, 67, 53, 1, 96, 53, 22, 1, 1, 1, 120, 122, 123, 75, 1, 1, 83, 1, 1, 1, 1, 90, 1, 117, 105, 111, 82, 1, 168, 119, 1, 125, 1, 1, 1, 135, 236, 1, 141, 1, 153, 281, 1, 1, 231, 1, 1, 1, 1, 236

Offset: 3

Author

Alois P. Heinz, Mar 23 2016

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 3..4555

Crossrefs

Cf. A000040, A270780.

Programs

Maple

a:= proc(n) option remember; local k, p; p:=ithprime(n);
      for k from p-3 by -1 do if irem(k!, p)=1 then return k fi od
    end:
seq(a(n), n=3..100);

Mathematica

lvk[n_]:=Module[{p=Prime[n],k},k=p-3;While[Mod[k!,p]!=1,k--];k]; Array[ lvk,80,3] (* Harvey P. Dale, Mar 01 2020 *)