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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 73 |
| 6 | 244 |
| 7 | 782 |
| 8 | 2415 |
| 9 | 7232 |
| 10 | 21122 |
| 11 | 60455 |
| 12 | 170228 |
| 13 | 473014 |
| 14 | 1300271 |
| 15 | 3543000 |
| 16 | 9584730 |
| 17 | 25776439 |
| 18 | 68985676 |
| 19 | 183892142 |
| 20 | 488588991 |
| 21 | 1294654352 |
| 22 | 3422964722 |
| 23 | 9033615431 |
| 24 | 23805283556 |
| 25 | 62654864998 |
| 26 | 164741271119 |
[1,2,6,21,73,244,782,2415,7232,21122,60455,170228, 473014,1300271,3543000,9584730,25776439,68985676, 183892142,488588991,1294654352,3422964722, 9033615431,23805283556,62654864998,164741271119] |