A064215 Least k such that k*6^n +/- 1 are twin primes.

1, 2, 2, 2, 18, 3, 33, 255, 212, 115, 147, 102, 17, 33, 308, 87, 198, 33, 172, 418, 210, 35, 158, 847, 1010, 292, 157, 1318, 263, 212, 642, 107, 458, 102, 17, 635, 735, 262, 2422, 3517, 1222, 605, 1362, 227, 367, 602, 207, 2023, 3925, 1857, 822, 137, 5568, 928

Offset: 1

Author

Robert G. Wilson v, Sep 21 2001

Keywords

• nonn

Comments

As n increases, a(n) is in average = 0.44*n^2. It appears that 62% of a(n)/n^2 are < 0.44. - Pierre CAMI, Jun 01 2012

Links

• R. J. Mathar, Table of n, a(n) for n = 1..240

Crossrefs

Cf. A063983.

Programs

Maple

A064215 := proc(n)
    for k from 1 do
        if isprime(k*6^n-1) and isprime(k*6^n+1) then
            return k;
        end if;
    end do:
end proc: # R. J. Mathar, Sep 17 2015

Mathematica

Table[ k = 1; While[ ! PrimeQ[ k*6^n + 1 ] || ! PrimeQ[ k*6^n - 1 ], k++ ]; k, {n, 50} ]