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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 27 |
| 4 | 109 |
| 5 | 453 |
| 6 | 1922 |
| 7 | 8284 |
| 8 | 36155 |
| 9 | 159435 |
| 10 | 709246 |
| 11 | 3178992 |
| 12 | 14343567 |
| 13 | 65099245 |
| 14 | 297015765 |
| 15 | 1361584755 |
| 16 | 6268757195 |
| 17 | 28975155915 |
| 18 | 134410918700 |
| 19 | 625578384150 |
| 20 | 2920488902795 |
| 21 | 13672762887465 |
| 22 | 64179220019365 |
| 23 | 301987822527627 |
[1,2,7,27,109,453,1922,8284,36155,159435,709246, 3178992,14343567,65099245,297015765,1361584755, 6268757195,28975155915,134410918700,625578384150, 2920488902795,13672762887465,64179220019365, 301987822527627] |