a(1) = 1; a(n) = -Sum_{k = 1..n-1} (n+k)!a(k)/(2k)!.
A007683
a(1) = 1; a(n) = -Sum_{k = 1..n-1} (n+k)!a(k)/(2k)!.
Terms
- a(0) =1a(1) =-3a(2) =3a(3) =9a(4) =21a(5) =-33a(6) =-1173a(7) =-13515a(8) =-113739a(9) =-532209a(10) =6284379a(11) =264830061a(12) =5897799141a(13) =104393462439
External references
- oeis: A007683