a(n) = Sum_{k=0..n} 3^k * 2^(n-k) * binomial(k,n-k)^2.
A387480
a(n) = Sum_{k=0..n} 3^k * 2^(n-k) * binomial(k,n-k)^2.
Terms
- a(0) =1a(1) =3a(2) =15a(3) =99a(4) =603a(5) =3807a(6) =24759a(7) =162243a(8) =1072683a(9) =7147359a(10) =47887767a(11) =322330995a(12) =2178055899a(13) =14765637663a(14) =100380161655a(15) =684061007139
External references
- oeis: A387480