Greatest prime dividing 2^n + n.

Terms

a(0) =3a(1) =3a(2) =11a(3) =5a(4) =37a(5) =7a(6) =5a(7) =11a(8) =521a(9) =47a(10) =71a(11) =79a(12) =547a(13) =911a(14) =32783a(15) =241a(16) =307a(17) =6899a(18) =24967a(19) =87383a(20) =457a(21) =4799a(22) =270601a(23) =7109a(24) =3728273a(25) =12497a(26) =1201a(27) =100613a(28) =2017a(29) =17318417