a(n) = (n!)^2 * Sum_{k=1..n} 1 / (k * ((n-k)!)^2).
A336291
a(n) = (n!)^2 * Sum_{k=1..n} 1 / (k * ((n-k)!)^2).
Terms
- a(0) =0a(1) =1a(2) =6a(3) =39a(4) =424a(5) =7905a(6) =227766a(7) =9324511a(8) =512970144a(9) =36452217969
External references
- oeis: A336291