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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 26 |
| 6 | 101 |
| 7 | 412 |
| 8 | 1756 |
| 9 | 7692 |
| 10 | 34350 |
| 11 | 155980 |
| 12 | 718312 |
| 13 | 3345890 |
| 14 | 15735091 |
| 15 | 74613107 |
| 16 | 356348561 |
| 17 | 1712593184 |
| 18 | 8276207120 |
| 19 | 40192085383 |
| 20 | 196045684833 |
| 21 | 960042529894 |
| 22 | 4718201036195 |
| 23 | 23263440797758 |
| 24 | 115042992517035 |
| 25 | 570463195069614 |
| 26 | 2835840294969867 |
| 27 | 14129895469191476 |
[1,1,2,7,26,101,412,1756,7692,34350,155980,718312, 3345890,15735091,74613107,356348561,1712593184, 8276207120,40192085383,196045684833,960042529894, 4718201036195,23263440797758,115042992517035, 570463195069614,2835840294969867, 14129895469191476] |