The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 30 |
| 4 | 360 |
| 5 | 6240 |
| 6 | 146160 |
| 7 | 4420080 |
| 8 | 166924800 |
| 9 | 7673823360 |
| 10 | 420850080000 |
| 11 | 27086342976000 |
| 12 | 2018319704755200 |
| 13 | 172142484203289600 |
| 14 | 16642276683198566400 |
| 15 | 1808459441303074560000 |
| 16 | 219273812138054209536000 |
| 17 | 29473992420094651613184000 |
[1,1,4,30,360,6240,146160,4420080,166924800, 7673823360,420850080000,27086342976000, 2018319704755200,172142484203289600, 16642276683198566400,1808459441303074560000, 219273812138054209536000, 29473992420094651613184000] |