The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | -6 |
| 4 | 30 |
| 5 | -150 |
| 6 | 806 |
| 7 | -4494 |
| 8 | 25822 |
| 9 | -151782 |
| 10 | 908502 |
| 11 | -5518590 |
| 12 | 33933774 |
| 13 | -210814422 |
| 14 | 1321230150 |
| 15 | -8343458286 |
| 16 | 53037407166 |
| 17 | -339111023046 |
| 18 | 2179407749558 |
| 19 | -14071216784862 |
| 20 | 91225811704750 |
| 21 | -593639364476598 |
[1,0,2,-6,30,-150,806,-4494,25822,-151782,908502, -5518590,33933774,-210814422,1321230150, -8343458286,53037407166,-339111023046, 2179407749558,-14071216784862,91225811704750, -593639364476598] |