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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 53 |
| 5 | 228 |
| 6 | 1209 |
| 7 | 7747 |
| 8 | 58225 |
| 9 | 500544 |
| 10 | 4832313 |
| 11 | 51687383 |
| 12 | 606215565 |
| 13 | 7731822692 |
| 14 | 106508476905 |
| 15 | 1575578081523 |
| 16 | 24906716310217 |
| 17 | 418953742412128 |
| 18 | 7470858290454729 |
| 19 | 140766571939157751 |
| 20 | 2794339758909240773 |
| 21 | 58286364420483563796 |
| 22 | 1274476812220456366841 |
| 23 | 29150033296842803410371 |
[1,2,5,15,53,228,1209,7747,58225,500544,4832313, 51687383,606215565,7731822692,106508476905, 1575578081523,24906716310217,418953742412128, 7470858290454729,140766571939157751, 2794339758909240773,58286364420483563796, 1274476812220456366841,29150033296842803410371] |