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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 65 |
| 4 | 490 |
| 5 | 4032 |
| 6 | 35244 |
| 7 | 321750 |
| 8 | 3035890 |
| 9 | 29395652 |
| 10 | 290621188 |
| 11 | 2922898706 |
| 12 | 29821640380 |
| 13 | 307994453600 |
| 14 | 3214454901480 |
| 15 | 33855533036865 |
| 16 | 359438259174930 |
| 17 | 3843173300937300 |
| 18 | 41351489731559700 |
| 19 | 447450028715934090 |
| 20 | 4866409456815200580 |
| 21 | 53171146669028038560 |
| 22 | 583400942149413843000 |
[1,2,10,65,490,4032,35244,321750,3035890,29395652, 290621188,2922898706,29821640380,307994453600, 3214454901480,33855533036865,359438259174930, 3843173300937300,41351489731559700, 447450028715934090,4866409456815200580, 53171146669028038560,583400942149413843000] |