a(n) = 3*a(n-1) - 4*a(n-2) + 6*a(n-3) - 4*a(n-4), with initial terms 0,1,2,4.

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =10a(5) =24a(6) =48a(7) =92a(8) =188a(9) =388a(10) =772a(11) =1524a(12) =3060a(13) =6164a(14) =12308a(15) =24532a(16) =49108a(17) =98388a(18) =196692a(19) =393044a(20) =786260a(21) =1573204a(22) =3146068a(23) =6290772a(24) =12582228a(25) =25167188a(26) =50333012a(27) =100660564a(28) =201323860a(29) =402658644