a(n) = Sum_{k=0..n} binomial(2n+1, 2k)*3^(n-k).
A102591
a(n) = Sum_{k=0..n} binomial(2n+1, 2k)*3^(n-k).
Terms
- a(0) =1a(1) =6a(2) =44a(3) =328a(4) =2448a(5) =18272a(6) =136384a(7) =1017984a(8) =7598336a(9) =56714752a(10) =423324672a(11) =3159738368a(12) =23584608256a(13) =176037912576
External references
- oeis: A102591