G.f.: (2-x)/((1+2x)(1-3x)); e.g.f.: exp(3x)+exp(-2x); a(n)=3^n+(-2)^n.

Terms

a(0) =2a(1) =1a(2) =13a(3) =19a(4) =97a(5) =211a(6) =793a(7) =2059a(8) =6817a(9) =19171a(10) =60073a(11) =175099a(12) =535537a(13) =1586131a(14) =4799353a(15) =14316139a(16) =43112257a(17) =129009091a(18) =387682633a(19) =1161737179a(20) =3487832977a(21) =10458256051a(22) =31385253913a(23) =94134790219a(24) =282446313697a(25) =847255055011