Greatest prime dividing 2^n - n for n>=2; a(1) = 1.

Terms

a(0) =1a(1) =2a(2) =5a(3) =3a(4) =3a(5) =29a(6) =11a(7) =31a(8) =503a(9) =13a(10) =97a(11) =1021a(12) =8179a(13) =1637a(14) =4679a(15) =13a(16) =8737a(17) =131063a(18) =524269a(19) =262139a(20) =2097131a(21) =2003a(22) =1423a(23) =2713a(24) =123817a(25) =170327a(26) =577a(27) =14983a(28) =564533a(29) =87481