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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 7 |
| 7 | 12 |
| 8 | 41 |
| 9 | 86 |
| 10 | 247 |
| 11 | 585 |
| 12 | 1548 |
| 13 | 3849 |
| 14 | 9896 |
| 15 | 25001 |
| 16 | 63724 |
| 17 | 161721 |
| 18 | 411257 |
| 19 | 1044878 |
| 20 | 2655719 |
| 21 | 6748972 |
| 22 | 17151849 |
| 23 | 43589578 |
| 24 | 110777391 |
| 25 | 281529169 |
| 26 | 715471992 |
| 27 | 1818293377 |
| 28 | 4620978640 |
| 29 | 11743694657 |
| 30 | 29845241080 |
| 31 | 75848270001 |
[1,0,1,1,2,7,12,41,86,247,585,1548,3849,9896, 25001,63724,161721,411257,1044878,2655719,6748972, 17151849,43589578,110777391,281529169,715471992, 1818293377,4620978640,11743694657,29845241080, 75848270001] |