The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 10 |
| 4 | 70 |
| 5 | 916 |
| 6 | 16636 |
| 7 | 494824 |
| 8 | 20486432 |
| 9 | 1320568624 |
| 10 | 119526633136 |
| 11 | 16466317431136 |
| 12 | 3210471529800448 |
| 13 | 940911157770908416 |
| 14 | 392559353168479443584 |
| 15 | 244017910517578226511616 |
| 16 | 216775189886094655708439296 |
| 17 | 284778404550532041821957456896 |
| 18 | 536018349047631899870416803595264 |
[1,1,2,10,70,916,16636,494824,20486432,1320568624, 119526633136,16466317431136,3210471529800448, 940911157770908416,392559353168479443584, 244017910517578226511616, 216775189886094655708439296, 284778404550532041821957456896, 536018349047631899870416803595264] |