Bertrand primes: a(n) is largest prime < 2*a(n-1) for n > 1, with a(1) = 2.

Terms

a(0) =2a(1) =3a(2) =5a(3) =7a(4) =13a(5) =23a(6) =43a(7) =83a(8) =163a(9) =317a(10) =631a(11) =1259a(12) =2503a(13) =5003a(14) =9973a(15) =19937a(16) =39869a(17) =79699a(18) =159389a(19) =318751a(20) =637499a(21) =1274989a(22) =2549951a(23) =5099893a(24) =10199767a(25) =20399531a(26) =40799041a(27) =81598067a(28) =163196129a(29) =326392249