a(n) = (2n-1)!! * Sum_{k=0..n-1}(-1)^k/(2k+1).
A024199
a(n) = (2n-1)!! * Sum_{k=0..n-1}(-1)^k/(2k+1).
Terms
- a(0) =0a(1) =1a(2) =2a(3) =13a(4) =76a(5) =789a(6) =7734a(7) =110937a(8) =1528920a(9) =28018665a(10) =497895210a(11) =11110528485a(12) =241792844580
External references
- oeis: A024199