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

Terms

a(0) =2a(1) =6a(2) =34a(3) =198a(4) =1154a(5) =6726a(6) =39202a(7) =228486a(8) =1331714a(9) =7761798a(10) =45239074a(11) =263672646a(12) =1536796802a(13) =8957108166a(14) =52205852194a(15) =304278004998