a(n) = ((2+sqrt(3))*(3+sqrt(3))^n + (2-sqrt(3))*(3-sqrt(3))^n)/2.

A162273

a(n) = ((2+sqrt(3))*(3+sqrt(3))^n + (2-sqrt(3))*(3-sqrt(3))^n)/2.

Terms

    a(0) =2a(1) =9a(2) =42a(3) =198a(4) =936a(5) =4428a(6) =20952a(7) =99144a(8) =469152a(9) =2220048a(10) =10505376a(11) =49711968a(12) =235239552a(13) =1113165504a(14) =5267555712a(15) =24926341248a(16) =117952713216a(17) =558158231808

External references