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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 36 |
| 3 | 186 |
| 4 | 891 |
| 5 | 3936 |
| 6 | 16236 |
| 7 | 62736 |
| 8 | 228411 |
| 9 | 786866 |
| 10 | 2576112 |
| 11 | 8045502 |
| 12 | 24054897 |
| 13 | 69070032 |
| 14 | 191013552 |
| 15 | 510099312 |
| 16 | 1318511727 |
| 17 | 3305802762 |
| 18 | 8055148012 |
| 19 | 19108956342 |
| 20 | 44204128413 |
| 21 | 99858745488 |
| 22 | 220591105668 |
| 23 | 477091381728 |
| 24 | 1011385901553 |
| 25 | 2103707920494 |
[1,6,36,186,891,3936,16236,62736,228411,786866, 2576112,8045502,24054897,69070032,191013552, 510099312,1318511727,3305802762,8055148012, 19108956342,44204128413,99858745488,220591105668, 477091381728,1011385901553,2103707920494] |