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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 42 |
| 5 | 130 |
| 6 | 397 |
| 7 | 1197 |
| 8 | 3566 |
| 9 | 10517 |
| 10 | 30760 |
| 11 | 89293 |
| 12 | 257397 |
| 13 | 737220 |
| 14 | 2099215 |
| 15 | 5945594 |
| 16 | 16756258 |
| 17 | 47004829 |
| 18 | 131286914 |
| 19 | 365203797 |
| 20 | 1012031772 |
| 21 | 2794446326 |
| 22 | 7690009600 |
| 23 | 21094325177 |
| 24 | 57687762889 |
| 25 | 157306741287 |
| 26 | 427777384499 |
| 27 | 1160250104637 |
| 28 | 3139067594584 |
| 29 | 8472525405830 |
| 30 | 22815639395641 |
[1,1,4,13,42,130,397,1197,3566,10517,30760,89293, 257397,737220,2099215,5945594,16756258,47004829, 131286914,365203797,1012031772,2794446326, 7690009600,21094325177,57687762889,157306741287, 427777384499,1160250104637,3139067594584, 8472525405830,22815639395641] |