a(n+3) = 5*a(n+2)-4*a(n+1)+a(n).

Terms

a(0) =0a(1) =1a(2) =3a(3) =11a(4) =44a(5) =179a(6) =730a(7) =2978a(8) =12149a(9) =49563a(10) =202197a(11) =824882a(12) =3365185a(13) =13728594a(14) =56007112a(15) =228486369a(16) =932131991a(17) =3802721591a(18) =15513566360a(19) =63289077427a(20) =258193843286