a(n) = 3*2^n + 5*(-1)^n.

Terms

a(0) =8a(1) =1a(2) =17a(3) =19a(4) =53a(5) =91a(6) =197a(7) =379a(8) =773a(9) =1531a(10) =3077a(11) =6139a(12) =12293a(13) =24571a(14) =49157a(15) =98299a(16) =196613a(17) =393211a(18) =786437a(19) =1572859a(20) =3145733a(21) =6291451a(22) =12582917a(23) =25165819a(24) =50331653a(25) =100663291a(26) =201326597a(27) =402653179a(28) =805306373a(29) =1610612731