0,10

Pierre CAMI, Table of n, a(n) for n = 0..1600

3*2^0*(2^1-1)-1=2 prime so k(0)=1 3*2^1*(2^1-1)-1=5 prime as 7 so k(1)=1 3*2^2*(2^1-1)-1=23 prime so k(2)=1

Sequence in context: A135910 A107333 A161642 this_sequence A098505 A021306 A125300

Adjacent sequences: A152138 A152139 A152140 this_sequence A152142 A152143 A152144

nonn

Pierre CAMI (pierre-cami(AT)orange.fr), Nov 26 2008