a(n) = Sum_{k=0..floor(n/2)} binomial(3*n-k,n-2*k).
A371742
a(n) = Sum_{k=0..floor(n/2)} binomial(3*n-k,n-2*k).
Terms
- a(0) =1a(1) =3a(2) =16a(3) =92a(4) =551a(5) =3380a(6) =21065a(7) =132771a(8) =843944a(9) =5399802a(10) =34731776a(11) =224361283a(12) =1454557294a(13) =9458829681a(14) =61670895633a(15) =403003997300
External references
- oeis: A371742