The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 44 |
| 3 | 840 |
| 4 | 23256 |
| 5 | 850080 |
| 6 | 38750400 |
| 7 | 2120489280 |
| 8 | 135566323200 |
| 9 | 9922550077440 |
| 10 | 818544054182400 |
| 11 | 75160674504115200 |
| 12 | 7604312776752384000 |
| 13 | 840608992488545280000 |
| 14 | 100812386907863414784000 |
| 15 | 13037431708092153922560000 |
| 16 | 1808675231786149165350912000 |
[1,4,44,840,23256,850080,38750400,2120489280, 135566323200,9922550077440,818544054182400, 75160674504115200,7604312776752384000, 840608992488545280000,100812386907863414784000, 13037431708092153922560000, 1808675231786149165350912000] |