A145691 a(n)= least x such that 3*2^n*(3*2^n-x)-1 and 3*2^n*(3*2^n-x)+1 are twin primes

1, 3, 6, 4, 18, 13, 24, 38, 11, 81, 14, 17, 66, 41, 41, 107, 59, 101, 34, 532, 209, 81, 119, 178, 53, 188, 244, 242, 66, 242, 157, 32, 16, 857, 21, 67, 233, 417, 727, 234, 189, 1381, 1854, 437, 129, 57, 749, 93, 531, 717, 21, 293, 311, 478, 874, 409, 686, 1667, 677, 52

Offset

1,2

Comments

As n increases sum a(n) from i=1 to n tends to (2*log(2)/3)^2*n*(n+1)*(2*n+1)/6 all verified values and certified primes in b145691 file

Links

Pierre CAMI, Table of n, a(n) for n = 1..600

Example

3*2*(3*2-1)-1=29 prime as 31 so a(1)=1

Crossrefs

A145690

Sequence in context: A357235 A307460 A128719 * A245767 A367302 A009782

Adjacent sequences: A145688 A145689 A145690 * A145692 A145693 A145694

Keyword

nonn

Author

Pierre CAMI, Oct 16 2008

Status

approved