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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 16 |
| 5 | 37 |
| 6 | 53 |
| 7 | 355 |
| 8 | 1118 |
| 9 | 3709 |
| 10 | 8536 |
| 11 | 12245 |
| 12 | 204456 |
| 13 | 421157 |
| 14 | 1467927 |
| 15 | 1889084 |
| 16 | 5246095 |
| 17 | 7135179 |
| 18 | 12381274 |
| 19 | 93804097 |
| 20 | 106185371 |
| 21 | 306174839 |
| 22 | 412360210 |
| 23 | 718535049 |
| 24 | 1130895259 |
| 25 | 2980325567 |
| 26 | 16032523094 |
| 27 | 35045371755 |
[0,1,1,5,16,37,53,355,1118,3709,8536,12245,204456, 421157,1467927,1889084,5246095,7135179,12381274, 93804097,106185371,306174839,412360210,718535049, 1130895259,2980325567,16032523094,35045371755] |