a(3)=1; a(n) = Sum_{i=1..n-3} binomial(n-4,i-1)*binomial(n,i+1)*a(i+2)*a(n-i)*i*(n-i-2)/(2*(n-1)) for n > 3.
A115047
a(3)=1; a(n) = Sum_{i=1..n-3} binomial(n-4,i-1)*binomial(n,i+1)*a(i+2)*a(n-i)*i*(n-i-2)/(2*(n-1)) for n > 3.
Terms
- a(0) =1a(1) =1a(2) =5a(3) =61a(4) =1379a(5) =49946a(6) =2648967a(7) =193530835a(8) =18634276859
External references
- oeis: A115047