a(n) = 5*a(n-2) + 2, a(0) = 1, a(1) = 2.

Terms

a(0) =1a(1) =2a(2) =7a(3) =12a(4) =37a(5) =62a(6) =187a(7) =312a(8) =937a(9) =1562a(10) =4687a(11) =7812a(12) =23437a(13) =39062a(14) =117187a(15) =195312a(16) =585937a(17) =976562a(18) =2929687a(19) =4882812a(20) =14648437a(21) =24414062a(22) =73242187a(23) =122070312a(24) =366210937a(25) =610351562a(26) =1831054687a(27) =3051757812a(28) =9155273437a(29) =15258789062