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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 9 |
| 3 | 34 |
| 4 | 104 |
| 5 | 326 |
| 6 | 995 |
| 7 | 2954 |
| 8 | 8671 |
| 9 | 25156 |
| 10 | 72256 |
| 11 | 205948 |
| 12 | 583109 |
| 13 | 1641570 |
| 14 | 4598725 |
| 15 | 12827750 |
| 16 | 35646792 |
| 17 | 98726370 |
| 18 | 272611239 |
| 19 | 750730314 |
| 20 | 2062369787 |
| 21 | 5653126280 |
| 22 | 15464460608 |
| 23 | 42225863096 |
| 24 | 115102499721 |
| 25 | 313264141570 |
| 26 | 851348070593 |
| 27 | 2310572001450 |
| 28 | 6263085581800 |
[1,2,9,34,104,326,995,2954,8671,25156,72256, 205948,583109,1641570,4598725,12827750,35646792, 98726370,272611239,750730314,2062369787, 5653126280,15464460608,42225863096,115102499721, 313264141570,851348070593,2310572001450, 6263085581800] |