a(n) = 2*a(n-1) - 1 with a(0)=14.

Terms

a(0) =14a(1) =27a(2) =53a(3) =105a(4) =209a(5) =417a(6) =833a(7) =1665a(8) =3329a(9) =6657a(10) =13313a(11) =26625a(12) =53249a(13) =106497a(14) =212993a(15) =425985a(16) =851969a(17) =1703937a(18) =3407873a(19) =6815745a(20) =13631489a(21) =27262977a(22) =54525953a(23) =109051905a(24) =218103809a(25) =436207617a(26) =872415233a(27) =1744830465a(28) =3489660929