a(n) = 2 * Sum_{k=0..n-1} binomial(n-1, k)*binomial(n+k, k).
A002003
a(n) = 2 * Sum_{k=0..n-1} binomial(n-1, k)*binomial(n+k, k).
Terms
- a(0) =0a(1) =2a(2) =8a(3) =38a(4) =192a(5) =1002a(6) =5336a(7) =28814a(8) =157184a(9) =864146a(10) =4780008a(11) =26572086a(12) =148321344a(13) =830764794a(14) =4666890936a(15) =26283115038a(16) =148348809216a(17) =838944980514
External references
- oeis: A002003