a(n) = n!*b(n), where b(n) = (1 + n - n^2)*b(n-2)/(n*(n-1)), b(0) = b(1) = 1.
A123025
a(n) = n!*b(n), where b(n) = (1 + n - n^2)*b(n-2)/(n*(n-1)), b(0) = b(1) = 1.
Terms
- a(0) =1a(1) =1a(2) =-1a(3) =-5a(4) =11a(5) =95a(6) =-319a(7) =-3895a(8) =17545a(9) =276545a(10) =-1561505a(11) =-30143405a(12) =204557155a(13) =4672227775a(14) =-37024845055a(15) =-976495604975
External references
- oeis: A123025