a(1)=1, a(n) = n*4^(n-1) + a(n-1).

Terms

a(0) =1a(1) =9a(2) =57a(3) =313a(4) =1593a(5) =7737a(6) =36409a(7) =167481a(8) =757305a(9) =3378745a(10) =14913081a(11) =65244729a(12) =283348537a(13) =1222872633a(14) =5249404473a(15) =22429273657a(16) =95443717689a(17) =404681363001