A071185 Smallest k such that prime(k*n)-k*prime(n) is prime.

7, 4, 2, 2, 2, 2, 6, 6, 4, 2, 2, 6, 2, 8, 2, 20, 4, 2, 2, 2, 6, 6, 8, 6, 6, 2, 4, 12, 2, 8, 6, 8, 2, 2, 6, 4, 2, 4, 6, 26, 24, 2, 2, 2, 4, 8, 18, 4, 2, 2, 4, 12, 4, 4, 18, 8, 6, 16, 4, 2, 2, 2, 4, 2, 2, 2, 4, 18, 6, 6, 4, 2, 4, 4, 6, 18, 2, 6, 2, 18, 4, 24, 6, 2, 6, 6, 18, 40, 2, 4, 2, 2, 18, 8, 34, 2, 2

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Mathematica

ppn[n_]:=Module[{k=1, prn=Prime[n]}, While[!PrimeQ[Prime[k n]-k prn], k++]; k]; Array[ppn, 100] (* Harvey P. Dale, May 22 2012 *)

Prog

(PARI) for(n=1, 210, s=1; while(isprime(prime(s*n)-s*prime(n))==0, s++); print1(s, ", "))
(Python)
from sympy import isprime, prime
def a(n):
    pn = prime(n); k = 1
    while not isprime(prime(k*n) - k*pn): k += 1
    return k
print([a(n) for n in range(1, 98)]) # Michael S. Branicky, Jul 04 2021

Crossrefs

Sequence in context: A188628 A021578 A273093 * A373018 A165244 A198356

Adjacent sequences: A071182 A071183 A071184 * A071186 A071187 A071188

Keyword

easy,nonn

Author

Benoit Cloitre, Jun 10 2002

Status

approved