Inverse Weigh transform of 3^(n-1).

Terms

a(0) =1a(1) =3a(2) =6a(3) =18a(4) =42a(5) =113a(6) =294a(7) =798a(8) =2128a(9) =5823a(10) =15918a(11) =43998a(12) =122010a(13) =340617a(14) =954394a(15) =2686728a(16) =7588770a(17) =21509824a(18) =61144062a(19) =174289710a(20) =498012094a(21) =1426229109a(22) =4092816966a(23) =11767220068a(24) =33890202192a(25) =97761550215a(26) =282424564744a(27) =817018885362