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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 14 |
| 5 | 70 |
| 6 | 370 |
| 7 | 2028 |
| 8 | 11452 |
| 9 | 66172 |
| 10 | 389416 |
| 11 | 2326202 |
| 12 | 14070268 |
| 13 | 86010680 |
| 14 | 530576780 |
| 15 | 3298906810 |
| 16 | 20653559846 |
| 17 | 130099026600 |
| 18 | 823979294284 |
| 19 | 5244162058026 |
| 20 | 33523117491920 |
| 21 | 215150177410088 |
| 22 | 1385839069134800 |
| 23 | 8956173544332434 |
| 24 | 58056703069399056 |
| 25 | 377396656568011618 |
| 26 | 2459614847765495754 |
| 27 | 16068572108927106202 |
[0,1,3,14,70,370,2028,11452,66172,389416,2326202, 14070268,86010680,530576780,3298906810, 20653559846,130099026600,823979294284, 5244162058026,33523117491920,215150177410088, 1385839069134800,8956173544332434, 58056703069399056,377396656568011618, 2459614847765495754,16068572108927106202] |