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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 57 |
| 5 | 232 |
| 6 | 1026 |
| 7 | 4535 |
| 8 | 20630 |
| 9 | 94513 |
| 10 | 439245 |
| 11 | 2054404 |
| 12 | 9687415 |
| 13 | 45916162 |
| 14 | 218754129 |
| 15 | 1046294862 |
| 16 | 5022478726 |
| 17 | 24180846137 |
| 18 | 116731776457 |
| 19 | 564812432954 |
| 20 | 2738508792600 |
| 21 | 13301878686123 |
| 22 | 64717290013574 |
| 23 | 315327835892313 |
| 24 | 1538432750901038 |
| 25 | 7514745797065005 |
| 26 | 36747136089253952 |
| 27 | 179872548740411287 |
[1,1,4,13,57,232,1026,4535,20630,94513,439245, 2054404,9687415,45916162,218754129,1046294862, 5022478726,24180846137,116731776457,564812432954, 2738508792600,13301878686123,64717290013574, 315327835892313,1538432750901038,7514745797065005, 36747136089253952,179872548740411287] |