The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 1 |
| 7 | 6 |
| 8 | 25 |
| 9 | 99 |
| 10 | 385 |
| 11 | 1472 |
| 12 | 5676 |
| 13 | 22101 |
| 14 | 87404 |
| 15 | 350097 |
| 16 | 1413251 |
| 17 | 5708158 |
| 18 | 22903161 |
| 19 | 90699398 |
| 20 | 352749035 |
| 21 | 1342638839 |
| 22 | 4990325414 |
| 23 | 18090636016 |
| 24 | 63933709870 |
| 25 | 220277491298 |
| 26 | 740170023052 |
| 27 | 2426954735273 |
| 28 | 7770739437179 |
| 29 | 24314436451415 |
| 30 | 74406425640743 |
| 31 | 222867051758565 |
| 32 | 653898059035166 |
[0,0,0,0,0,1,6,25,99,385,1472,5676,22101,87404, 350097,1413251,5708158,22903161,90699398, 352749035,1342638839,4990325414,18090636016, 63933709870,220277491298,740170023052, 2426954735273,7770739437179,24314436451415, 74406425640743,222867051758565,653898059035166] |