The (1,1)-entry of the matrix A^n, where A = [0,1;2,3].

Terms

a(0) =0a(1) =2a(2) =6a(3) =22a(4) =78a(5) =278a(6) =990a(7) =3526a(8) =12558a(9) =44726a(10) =159294a(11) =567334a(12) =2020590a(13) =7196438a(14) =25630494a(15) =91284358a(16) =325114062a(17) =1157910902a(18) =4123960830a(19) =14687704294a(20) =52311034542a(21) =186308512214a(22) =663547605726