a(n) = 2*binomial(3*n, n) - Sum_{k=0..n} binomial(3*n, k).
A047098
a(n) = 2*binomial(3*n, n) - Sum_{k=0..n} binomial(3*n, k).
Terms
- a(0) =1a(1) =2a(2) =8a(3) =38a(4) =196a(5) =1062a(6) =5948a(7) =34120a(8) =199316a(9) =1181126a(10) =7080928a(11) =42860534a(12) =261542752a(13) =1607076200a(14) =9934255472a(15) =61732449648a(16) =385393229460
External references
- oeis: A047098