1,1

2*2+1=5, 5 prime so a(1)=2

2*2*3+1=13, 13 prime so a(2)=3

2*2*3*5+1=61, 61 prime so a(3)=5

Cf. A119833 A119835.

Sequence in context: A028867 A104154 A123214 this_sequence A095180 A101989 A098922

Adjacent sequences: A119831 A119832 A119833 this_sequence A119835 A119836 A119837

nonn

Pierre CAMI (pierrecami(AT)tele2.fr), May 25 2006