a(n) = (2*n)!*Sum_{k = 0..n} (-1)^k/(2*k)!.
A275651
a(n) = (2*n)!*Sum_{k = 0..n} (-1)^k/(2*k)!.
Terms
- a(0) =1a(1) =1a(2) =13a(3) =389a(4) =21785a(5) =1960649a(6) =258805669a(7) =47102631757
External references
- oeis: A275651
A275651
a(n) = (2*n)!*Sum_{k = 0..n} (-1)^k/(2*k)!.