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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 23 |
| 5 | 62 |
| 6 | 269 |
| 7 | 850 |
| 8 | 3891 |
| 9 | 13419 |
| 10 | 62990 |
| 11 | 229483 |
| 12 | 1093201 |
| 13 | 4139300 |
| 14 | 19918865 |
| 15 | 77643783 |
| 16 | 376413282 |
| 17 | 1501052044 |
| 18 | 7317882715 |
| 19 | 29721764794 |
| 20 | 145523007631 |
| 21 | 600006212256 |
| 22 | 2947600993255 |
| 23 | 12306920472227 |
| 24 | 60619759341056 |
| 25 | 255809804792113 |
| 26 | 1262717951385575 |
| 27 | 5377423110200973 |
| 28 | 26589798486133635 |
[1,1,3,6,23,62,269,850,3891,13419,62990,229483, 1093201,4139300,19918865,77643783,376413282, 1501052044,7317882715,29721764794,145523007631, 600006212256,2947600993255,12306920472227, 60619759341056,255809804792113,1262717951385575, 5377423110200973,26589798486133635] |