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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 42 |
| 5 | 154 |
| 6 | 607 |
| 7 | 2457 |
| 8 | 10096 |
| 9 | 42635 |
| 10 | 181063 |
| 11 | 783097 |
| 12 | 3404412 |
| 13 | 14968062 |
| 14 | 66152869 |
| 15 | 294491008 |
| 16 | 1317205403 |
| 17 | 5921288039 |
| 18 | 26725832213 |
| 19 | 121082990990 |
| 20 | 550409795013 |
| 21 | 2509499048267 |
| 22 | 11473203958203 |
| 23 | 52583234951938 |
| 24 | 241548502218746 |
| 25 | 1111869845478979 |
| 26 | 5127900552363954 |
| 27 | 23691050694984716 |
[1,1,4,11,42,154,607,2457,10096,42635,181063, 783097,3404412,14968062,66152869,294491008, 1317205403,5921288039,26725832213,121082990990, 550409795013,2509499048267,11473203958203, 52583234951938,241548502218746,1111869845478979, 5127900552363954,23691050694984716] |