a(n) = 120*2^n - 95.

Terms

a(0) =25a(1) =145a(2) =385a(3) =865a(4) =1825a(5) =3745a(6) =7585a(7) =15265a(8) =30625a(9) =61345a(10) =122785a(11) =245665a(12) =491425a(13) =982945a(14) =1965985a(15) =3932065a(16) =7864225a(17) =15728545a(18) =31457185a(19) =62914465a(20) =125829025a(21) =251658145a(22) =503316385a(23) =1006632865a(24) =2013265825a(25) =4026531745a(26) =8053063585a(27) =16106127265a(28) =32212254625a(29) =64424509345