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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 14 |
| 5 | 40 |
| 6 | 128 |
| 7 | 369 |
| 8 | 1214 |
| 9 | 3516 |
| 10 | 12776 |
| 11 | 40534 |
| 12 | 137404 |
| 13 | 463232 |
| 14 | 1602348 |
| 15 | 5216253 |
| 16 | 17753898 |
| 17 | 58597316 |
| 18 | 212150928 |
| 19 | 710453534 |
| 20 | 2366853608 |
| 21 | 8584498376 |
| 22 | 30026959300 |
| 23 | 100396304016 |
| 24 | 333997297900 |
| 25 | 1157269900344 |
| 26 | 3852364562536 |
| 27 | 13917848281928 |
| 28 | 45618032373712 |
[1,1,2,5,14,40,128,369,1214,3516,12776,40534, 137404,463232,1602348,5216253,17753898,58597316, 212150928,710453534,2366853608,8584498376, 30026959300,100396304016,333997297900, 1157269900344,3852364562536,13917848281928, 45618032373712] |