a(n) = (3^n/n!)*Product_{k=0..n-1} (3*k + 1). 3-central binomial coefficients.
A004987
a(n) = (3^n/n!)*Product_{k=0..n-1} (3*k + 1). 3-central binomial coefficients.
Terms
- a(0) =1a(1) =3a(2) =18a(3) =126a(4) =945a(5) =7371a(6) =58968a(7) =480168a(8) =3961386a(9) =33011550a(10) =277297020a(11) =2344420260a(12) =19927572210a(13) =170150808870
External references
- oeis: A004987