a(2n) = a(2n-1) + 2a(2n-2), a(2n+1) = a(2n) + a(2n-1), with a(1) = 2 and a(2) = 3.

Terms

a(0) =2a(1) =3a(2) =5a(3) =11a(4) =16a(5) =38a(6) =54a(7) =130a(8) =184a(9) =444a(10) =628a(11) =1516a(12) =2144a(13) =5176a(14) =7320a(15) =17672a(16) =24992a(17) =60336a(18) =85328a(19) =206000a(20) =291328a(21) =703328a(22) =994656a(23) =2401312a(24) =3395968a(25) =8198592a(26) =11594560a(27) =27991744a(28) =39586304a(29) =95569792