a(n) is the largest prime factor of n*2^n+1 for n>0, and a(0)=1.

Terms

a(0) =1a(1) =3a(2) =3a(3) =5a(4) =13a(5) =23a(6) =11a(7) =23a(8) =683a(9) =419a(10) =19a(11) =1733a(12) =199a(13) =11833a(14) =487a(15) =997a(16) =61681a(17) =4691a(18) =211a(19) =5279a(20) =7541a(21) =1914791a(22) =7177a(23) =607a(24) =5233a(25) =6689a(26) =2373919a(27) =336823a(28) =8937209a(29) =6051013