a(n+3) = 3*a(n+2) + 5*a(n+1) + a(n), a(0) = 0, a(1) = 1, a(2) = 3.

Terms

a(0) =0a(1) =1a(2) =3a(3) =14a(4) =58a(5) =247a(6) =1045a(7) =4428a(8) =18756a(9) =79453a(10) =336567a(11) =1425722a(12) =6039454a(13) =25583539a(14) =108373609a(15) =459077976a(16) =1944685512a(17) =8237820025a(18) =34895965611a(19) =147821682470a(20) =626182695490