A182030 Least odd number k such that 3*k*2^n-1 and 3*k*2^n+1 are twin primes.

1, 1, 3, 5, 27, 1, 3, 19, 15, 5, 33, 55, 123, 15, 115, 39, 127, 1, 23, 149, 27, 11, 393, 81, 255, 125, 27, 129, 15, 115, 227, 195, 125, 89, 247, 71, 143, 1031, 55, 89, 85, 365, 3, 49, 283, 135, 497, 59, 647, 309, 375, 399, 667, 111, 173, 355, 195, 219, 43, 49

Offset: 1

Author

Pierre CAMI, Apr 07 2012

Keywords

• nonn

Comments

54% of a(n) for n=1 to 1755 are < 0.1*n^2.

Links

• Pierre CAMI, Table of n, a(n) for n = 1..1755

Crossrefs

Cf. A210651.

Programs

Mathematica

lon[n_]:=Module[{k=1,n2=3*2^n},While[!PrimeQ[k*n2-1]||!PrimeQ[k*n2+1], k= k+2];k]; Array[lon,60] (* Harvey P. Dale, Nov 27 2015 *)