a(n) = 2^(2n+1) * binomial(3n,n)/(2n+1).
A098272
a(n) = 2^(2n+1) * binomial(3n,n)/(2n+1).
Terms
- a(0) =2a(1) =8a(2) =96a(3) =1536a(4) =28160a(5) =559104a(6) =11698176a(7) =254017536a(8) =5670567936a(9) =129328742400
External references
- oeis: A098272
A098272
a(n) = 2^(2n+1) * binomial(3n,n)/(2n+1).