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A064215
Least k such that k*6^n +/- 1 are twin primes.
6
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
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
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Sep 21 2001
STATUS
approved