A064215 - OEIS

%I #16 Sep 17 2015 06:21:13

%S 1,2,2,2,18,3,33,255,212,115,147,102,17,33,308,87,198,33,172,418,210,

%T 35,158,847,1010,292,157,1318,263,212,642,107,458,102,17,635,735,262,

%U 2422,3517,1222,605,1362,227,367,602,207,2023,3925,1857,822,137,5568,928

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

%C 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

%H R. J. Mathar, <a href="/A064215/b064215.txt">Table of n, a(n) for n = 1..240</a>

%p A064215 := proc(n)

%p     for k from 1 do

%p         if isprime(k*6^n-1) and isprime(k*6^n+1) then

%p             return k;

%p         end if;

%p     end do:

%p end proc: # _R. J. Mathar_, Sep 17 2015

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

%Y Cf. A063983.

%K nonn

%O 1,2

%A _Robert G. Wilson v_, Sep 21 2001