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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 12 |
| 5 | 33 |
| 6 | 99 |
| 7 | 319 |
| 8 | 980 |
| 9 | 2966 |
| 10 | 8776 |
| 11 | 26196 |
| 12 | 77510 |
| 13 | 234031 |
| 14 | 708205 |
| 15 | 2132677 |
| 16 | 6421621 |
| 17 | 19225005 |
| 18 | 57566221 |
| 19 | 172152197 |
| 20 | 515505478 |
| 21 | 1541863101 |
| 22 | 4618183861 |
| 23 | 13838387169 |
| 24 | 41464367959 |
| 25 | 124065165161 |
| 26 | 371090483661 |
| 27 | 1110570396650 |
[1,2,5,12,33,99,319,980,2966,8776,26196,77510, 234031,708205,2132677,6421621,19225005,57566221, 172152197,515505478,1541863101,4618183861, 13838387169,41464367959,124065165161,371090483661, 1110570396650] |