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

1,2

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

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} ]

Crossrefs

Cf. A063983.

Sequence in context: A214756 A079007 A349642 * A358633 A087238 A226935

Adjacent sequences: A064212 A064213 A064214 * A064216 A064217 A064218

Keyword

nonn

Author

Robert G. Wilson v, Sep 21 2001

Status

approved