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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 34 |
| 5 | 116 |
| 6 | 414 |
| 7 | 1520 |
| 8 | 5801 |
| 9 | 22425 |
| 10 | 88356 |
| 11 | 354015 |
| 12 | 1436161 |
| 13 | 5883984 |
| 14 | 24364534 |
| 15 | 101756744 |
| 16 | 428049139 |
| 17 | 1812818242 |
| 18 | 7726376444 |
| 19 | 33107102100 |
| 20 | 142560071609 |
| 21 | 616726081964 |
| 22 | 2679247585672 |
| 23 | 11683377518921 |
| 24 | 51128959743600 |
| 25 | 224495464642072 |
| 26 | 988696444896896 |
| 27 | 4366576279940710 |
| 28 | 19336461231673449 |
[1,1,4,10,34,116,414,1520,5801,22425,88356,354015, 1436161,5883984,24364534,101756744,428049139, 1812818242,7726376444,33107102100,142560071609, 616726081964,2679247585672,11683377518921, 51128959743600,224495464642072,988696444896896, 4366576279940710,19336461231673449] |