Floor(r*a(n-1)) + floor(r*a(n-2)), where r = 5/2, a(0) = 1, a(1) = 1.

Terms

a(0) =1a(1) =1a(2) =4a(3) =12a(4) =40a(5) =130a(6) =425a(7) =1387a(8) =4529a(9) =14789a(10) =48294a(11) =157707a(12) =515002a(13) =1681772a(14) =5491935a(15) =17934267a(16) =58565504a(17) =191249427a(18) =624537327a(19) =2039466884a(20) =6660010527a(21) =21748693527a(22) =71021760134a(23) =231926134152a(24) =757369735715