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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 7 |
| 5 | 9 |
| 6 | 47 |
| 7 | 80 |
| 8 | 492 |
| 9 | 985 |
| 10 | 7197 |
| 11 | 16430 |
| 12 | 139316 |
| 13 | 361737 |
| 14 | 3425683 |
| 15 | 9939134 |
| 16 | 103484333 |
| 17 | 329541459 |
| 18 | 3747921857 |
| 19 | 12980700318 |
| 20 | 159811532315 |
| 21 | 598410986533 |
| 22 | 7902918548186 |
| 23 | 31781977111506 |
| 24 | 447462660895105 |
| 25 | 1920559118957107 |
| 26 | 28699615818386524 |
| 27 | 130838216971937408 |
[1,1,2,2,7,9,47,80,492,985,7197,16430,139316, 361737,3425683,9939134,103484333,329541459, 3747921857,12980700318,159811532315,598410986533, 7902918548186,31781977111506,447462660895105, 1920559118957107,28699615818386524, 130838216971937408] |