a(n) = Sum_{k=0..n-1} binomial(n-1,k)*binomial(n+k,k). Also a(n) = T(n,n), array T as in A049600.
A047781
a(n) = Sum_{k=0..n-1} binomial(n-1,k)*binomial(n+k,k). Also a(n) = T(n,n), array T as in A049600.
Terms
- a(0) =0a(1) =1a(2) =4a(3) =19a(4) =96a(5) =501a(6) =2668a(7) =14407a(8) =78592a(9) =432073a(10) =2390004a(11) =13286043a(12) =74160672a(13) =415382397a(14) =2333445468a(15) =13141557519a(16) =74174404608a(17) =419472490257
External references
- oeis: A047781