The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 12 |
| 4 | 132 |
| 5 | 2200 |
| 6 | 50280 |
| 7 | 1482768 |
| 8 | 54171376 |
| 9 | 2381590944 |
| 10 | 123292821600 |
| 11 | 7390709937600 |
| 12 | 506182300962624 |
| 13 | 39180896544097152 |
| 14 | 3396777800819754624 |
| 15 | 327323946734658720000 |
| 16 | 34831825328790915321600 |
[0,1,2,12,132,2200,50280,1482768,54171376, 2381590944,123292821600,7390709937600, 506182300962624,39180896544097152, 3396777800819754624,327323946734658720000, 34831825328790915321600] |