a(n) = 2*a(n-1) + 6*a(n-2), a(0) = 0, a(1) = 1.

Terms

a(0) =0a(1) =1a(2) =2a(3) =10a(4) =32a(5) =124a(6) =440a(7) =1624a(8) =5888a(9) =21520a(10) =78368a(11) =285856a(12) =1041920a(13) =3798976a(14) =13849472a(15) =50492800a(16) =184082432a(17) =671121664a(18) =2446737920a(19) =8920205824a(20) =32520839168a(21) =118562913280a(22) =432250861568