A204911 The prime q>=5 such that n divides p-q, where p>q is the least prime for which such a prime q exists.

5, 5, 5, 7, 7, 5, 5, 5, 5, 7, 7, 5, 5, 5, 7, 7, 7, 5, 5, 11, 5, 7, 7, 5, 11, 5, 5, 13, 13, 7, 5, 5, 5, 7, 13, 5, 5, 5, 5, 7, 7, 5, 11, 17, 7, 7, 7, 5, 5, 11, 5, 7, 7, 5, 17, 5, 13, 13, 13, 7, 5, 5, 5, 7, 7, 5, 5, 5, 11, 13, 7, 7, 5, 5, 7, 7, 13, 5, 5, 17, 5, 7, 7, 5, 11, 11, 5, 13, 13, 7, 11, 5, 5

Offset: 1

Author

Clark Kimberling, Jan 20 2012

Keywords

• nonn

Comments

For a guide to related sequences, see A204892.

Links

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

Crossrefs

Cf. A204908, A204900, A204892.

Programs

Maple

f:= proc(n) local V,q,r;
  V:= Array(0..n-1); q:= 4;
  do
   q:= nextprime(q);
   r:= q mod n;
   if V[r] = 0 then V[r]:= q
   else return V[r]
   fi
  od
end proc:
map(f, [$1..100]); # Robert Israel, Jul 24 2018

Mathematica

(See the program at A204908.)

Python

from sympy import nextprime
def a(n):
    V, q = [0 for _ in range(n)], 4
    while True:
        q = nextprime(q)
        r = q%n
        if V[r] == 0: V[r] = q
        else: return int(V[r])
print([a(n) for n in range(1, 94)]) # Michael S. Branicky, Jun 25 2024 after Robert Israel

Extensions

More terms from Robert G. Wilson v, Jul 24 2018