a(n) = (1/n^2) * Sum_{k = 0..n-1} (2*k+1)*(D_k)^2, where D_0, D_1, ... are central Delannoy numbers given by A001850.
A178808
a(n) = (1/n^2) * Sum_{k = 0..n-1} (2*k+1)*(D_k)^2, where D_0, D_1, ... are central Delannoy numbers given by A001850.
Terms
- a(0) =1a(1) =7a(2) =97a(3) =1791a(4) =38241a(5) =892039a(6) =22092673a(7) =571387903a(8) =15271248769a(9) =418796912007
External references
- oeis: A178808