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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 7 |
| 3 | 16 |
| 4 | 55 |
| 5 | 235 |
| 6 | 856 |
| 7 | 2664 |
| 8 | 9055 |
| 9 | 37417 |
| 10 | 151431 |
| 11 | 533452 |
| 12 | 1825972 |
| 13 | 7141860 |
| 14 | 29778280 |
| 15 | 113688592 |
| 16 | 400940751 |
| 17 | 1499506693 |
| 18 | 6185139781 |
| 19 | 24862774872 |
| 20 | 91529003839 |
| 21 | 334939413067 |
| 22 | 1338383383444 |
| 23 | 5510330536000 |
| 24 | 21217042841668 |
| 25 | 77850045234108 |
| 26 | 300471644949940 |
[1,3,7,16,55,235,856,2664,9055,37417,151431, 533452,1825972,7141860,29778280,113688592, 400940751,1499506693,6185139781,24862774872, 91529003839,334939413067,1338383383444, 5510330536000,21217042841668,77850045234108, 300471644949940] |