1,2

2*((6*1)^1) + 1 = 13 prime, so a(1)=1

2*((6*2)^1) + 1 = 25 = 5^2

2*((6*2)^2) + 1 = 289 = 17^2

2*((6*2)^3) + 1 = 3457 prime, so a(2)=3

Sequence in context: A086249 A016569 A072801 this_sequence A139436 A084642 A010281

Adjacent sequences: A098869 A098870 A098871 this_sequence A098873 A098874 A098875

nonn

Pierre CAMI (pierrecami(AT)tele2.fr), Oct 13 2004