a(n) = Sum_{k=0..n} C(n,k) * (1 + 3^k)^(n-k).
A244755
a(n) = Sum_{k=0..n} C(n,k) * (1 + 3^k)^(n-k).
Terms
- a(0) =1a(1) =3a(2) =13a(3) =87a(4) =985a(5) =19563a(6) =697573a(7) =44195007a(8) =4985202865a(9) =987432857043
External references
- oeis: A244755