1,2

1*2*(2^2-1)+1=7 prime so k(1)=1

2*3*(2^3-1)+1=43 prime so k(2)=2

3*4*(2^5-1)+1=373 prime so k(3)=3

Sequence in context: A124442 A088611 A137765 this_sequence A112979 A092972 A081526

Adjacent sequences: A104035 A104036 A104037 this_sequence A104039 A104040 A104041

more,nonn

Pierre CAMI (pierrecami(AT)tele2.fr), Mar 31 2005