a(0)=1; thereafter a(n) = -2*Sum_{k=1..n} binomial(2n,2k)*a(n-k).
A210657
a(0)=1; thereafter a(n) = -2*Sum_{k=1..n} binomial(2n,2k)*a(n-k).
Terms
- a(0) =1a(1) =-2a(2) =22a(3) =-602a(4) =30742a(5) =-2523002a(6) =303692662a(7) =-50402079002
External references
- oeis: A210657