a(n) = 15*2^n.

Terms

a(0) =15a(1) =30a(2) =60a(3) =120a(4) =240a(5) =480a(6) =960a(7) =1920a(8) =3840a(9) =7680a(10) =15360a(11) =30720a(12) =61440a(13) =122880a(14) =245760a(15) =491520a(16) =983040a(17) =1966080a(18) =3932160a(19) =7864320a(20) =15728640a(21) =31457280a(22) =62914560a(23) =125829120a(24) =251658240a(25) =503316480a(26) =1006632960a(27) =2013265920a(28) =4026531840a(29) =8053063680