| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 4 |
| 6 | 12 |
| 7 | 29 |
| 8 | 110 |
| 9 | 290 |
| 10 | 1274 |
| 11 | 3532 |
| 12 | 17136 |
| 13 | 49100 |
| 14 | 255816 |
| 15 | 750325 |
| 16 | 4124406 |
| 17 | 12310294 |
| 18 | 70549050 |
| 19 | 213446666 |
| 20 | 1264752060 |
| 21 | 3868253164 |
| 22 | 23555382240 |
| 23 | 72686739116 |
| 24 | 452806924752 |
[1,1,1,2,4,12,29,110,290,1274,3532,17136,49100, 255816,750325,4124406,12310294,70549050,213446666, 1264752060,3868253164,23555382240,72686739116, 452806924752] |