a(0) = 1, a(1) = 5, a(2) = 13; a(n) = 2*a(n-1) + 2, n > 2.

Terms

a(0) =1a(1) =5a(2) =13a(3) =28a(4) =58a(5) =118a(6) =238a(7) =478a(8) =958a(9) =1918a(10) =3838a(11) =7678a(12) =15358a(13) =30718a(14) =61438a(15) =122878a(16) =245758a(17) =491518a(18) =983038a(19) =1966078a(20) =3932158a(21) =7864318a(22) =15728638a(23) =31457278a(24) =62914558a(25) =125829118a(26) =251658238a(27) =503316478a(28) =1006632958a(29) =2013265918