Define b(0)=28, b(n+1)=2*b(n)+1; sequence gives largest prime factor of b(n).

Terms

a(0) =7a(1) =19a(2) =23a(3) =11a(4) =463a(5) =103a(6) =53a(7) =1237a(8) =571a(9) =101a(10) =5939a(11) =6599a(12) =239a(13) =313a(14) =95027a(15) =1223a(16) =1900543a(17) =281a(18) =43441a(19) =1699a(20) =2339131a(21) =2896067a(22) =1283a(23) =3229a(24) =3021983a(25) =5317369a(26) =389231411a(27) =32869a(28) =301999a(29) =2339