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

Terms

a(0) =1a(1) =2a(2) =-1a(3) =8a(4) =-19a(5) =62a(6) =-181a(7) =548a(8) =-1639a(9) =4922a(10) =-14761a(11) =44288a(12) =-132859a(13) =398582a(14) =-1195741a(15) =3587228a(16) =-10761679a(17) =32285042a(18) =-96855121a(19) =290565368a(20) =-871696099a(21) =2615088302a(22) =-7845264901a(23) =23535794708a(24) =-70607384119a(25) =211822152362a(26) =-635466457081