A242860 a(n) is the least k >= 2 such that k is neither a square modulo n nor a primitive root (mod n), or 0 if no such value exists.

0, 2, 0, 2, 6, 2, 3, 2, 10, 2, 5, 6, 2, 2, 0, 2, 8, 2, 2, 2, 22, 2, 5, 2, 3, 2, 12, 2, 6, 2, 2, 6, 2, 2, 6, 2, 2, 2, 3, 2, 2, 2, 2, 10, 46, 2, 6, 2, 2, 2, 23, 2, 2, 2, 2, 2, 58, 2, 8, 6, 2, 2, 2, 2, 3, 2, 2, 2, 14, 2, 7, 2, 2, 2, 2, 2, 12, 2, 3, 3, 82, 2, 2, 2

Offset: 3

Author

Arkadiusz Wesolowski, May 24 2014

Keywords

• nonn

Comments

a(A019434(n)) = 0 for n >= 1.

Links

• Eric Weisstein's World of Mathematics, Primitive Root

Crossrefs

Cf. A028730, A136804, A136806.

Programs

Magma

lst:=[]; for n in [3..86] do v:=0; for r in [2..n-1] do if not IsSquare(ResidueClassRing(n)! r) and not IsPrimitive(r, n) then v:=r; break; end if; end for; lst:=Append(lst, v); end for; lst;