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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 48 |
| 5 | 211 |
| 6 | 970 |
| 7 | 4594 |
| 8 | 22311 |
| 9 | 110473 |
| 10 | 555561 |
| 11 | 2829918 |
| 12 | 14570666 |
| 13 | 75708835 |
| 14 | 396481070 |
| 15 | 2090558864 |
| 16 | 11089276706 |
| 17 | 59135014252 |
| 18 | 316836936662 |
| 19 | 1704764660218 |
| 20 | 9207671377450 |
| 21 | 49904141524184 |
| 22 | 271325301723223 |
| 23 | 1479427708380368 |
| 24 | 8088057338101442 |
| 25 | 44325245804200151 |
[1,1,3,12,48,211,970,4594,22311,110473,555561, 2829918,14570666,75708835,396481070,2090558864, 11089276706,59135014252,316836936662, 1704764660218,9207671377450,49904141524184, 271325301723223,1479427708380368,8088057338101442, 44325245804200151] |