The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 28 |
| 4 | 340 |
| 5 | 3108 |
| 6 | 106932 |
| 7 | 2732340 |
| 8 | 236790060 |
| 9 | 19703562780 |
| 10 | 3419598096420 |
| 11 | 674127752953380 |
| 12 | 264134168649181380 |
| 13 | 95825592671995399620 |
| 14 | 67662122741507082338220 |
| 15 | 50556978553034312461203420 |
| 16 | 69259146896604886347745839660 |
| 17 | 104191622563656655781003976625020 |
[1,2,6,28,340,3108,106932,2732340,236790060, 19703562780,3419598096420,674127752953380, 264134168649181380,95825592671995399620, 67662122741507082338220, 50556978553034312461203420, 69259146896604886347745839660, 104191622563656655781003976625020] |