A377939 Nonsquares k such that A377938(k) is not a prime.

3, 5, 7, 17, 19, 22, 23, 29, 31, 33, 37, 43, 47, 53, 55, 71, 85, 87, 89, 91, 102, 103, 105, 106, 109, 111, 112, 113, 115, 116, 117, 122, 123, 133, 139, 141, 143, 145, 149, 153, 155, 157, 162, 163, 167, 175, 177, 191, 193, 199, 201, 203, 209, 211, 221, 223, 233, 239, 241, 243, 245, 247, 249, 253

Offset: 1

Author

Robert Israel, Nov 11 2024

Keywords

• nonn

Comments

Numbers k such that k is a primitive root modulo some nonprime x > k but not modulo any prime between k and x.

Numbers k such that 0 < A377938(k) < A023049(k).

Examples

			a(3) = 7 is a term because 7 is a primitive root mod 10, while the least prime > 7 for which 7 is a primitive root is 11.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A023049, A377938.

Programs

Maple

filter:= proc(n) local k;
  if issqr(n) then return false fi;
  for k from n+1 do
    if igcd(k,n) = 1 and numtheory:-order(n,k) = numtheory:-phi(k) then return not isprime(k) fi
  od
end proc:
select(filter, [$2..1000]);