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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 10 |
| 2 | 75 |
| 3 | 440 |
| 4 | 2255 |
| 5 | 10362 |
| 6 | 43945 |
| 7 | 174460 |
| 8 | 656370 |
| 9 | 2359500 |
| 10 | 8158722 |
| 11 | 27275040 |
| 12 | 88524930 |
| 13 | 279892380 |
| 14 | 864508590 |
| 15 | 2614740216 |
| 16 | 7759693095 |
| 17 | 22634343270 |
| 18 | 64990287285 |
| 19 | 183929970840 |
| 20 | 513661549401 |
| 21 | 1416970676550 |
[1,10,75,440,2255,10362,43945,174460,656370, 2359500,8158722,27275040,88524930,279892380, 864508590,2614740216,7759693095,22634343270, 64990287285,183929970840,513661549401, 1416970676550] |