1,4

As n increases (sum k(n) for i=1 to n)/(sum n for i=1 to n) tends to log(2)

Pierre CAMI, Table of n, a(n) for n = 1..2000

3*2^0*(2^1-1)-1=2 prime so k(1)=0 3*2^1*(2^2-1)-1=17 prime as 19 so k(2)=1 3*2^1*(2^3-1)-1=41 prime as 43 so k(2)=1

Sequence in context: A029027 A035448 A060969 this_sequence A030699 A083802 A100881

Adjacent sequences: A152159 A152160 A152161 this_sequence A152163 A152164 A152165

nonn

Pierre CAMI (pierre-cami(AT)orange.fr), Nov 27 2008