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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 28 |
| 4 | 120 |
| 5 | 536 |
| 6 | 2457 |
| 7 | 11481 |
| 8 | 54360 |
| 9 | 259969 |
| 10 | 1252706 |
| 11 | 6072223 |
| 12 | 29572252 |
| 13 | 144564197 |
| 14 | 708884636 |
| 15 | 3484931078 |
| 16 | 17168524909 |
| 17 | 84731554148 |
| 18 | 418805940619 |
| 19 | 2072716595002 |
| 20 | 10269460176509 |
| 21 | 50929639896861 |
| 22 | 252786813629413 |
| 23 | 1255605670244016 |
| 24 | 6240630233618970 |
| 25 | 31034662772521170 |
| 26 | 154411925525049741 |
[1,2,7,28,120,536,2457,11481,54360,259969,1252706, 6072223,29572252,144564197,708884636,3484931078, 17168524909,84731554148,418805940619, 2072716595002,10269460176509,50929639896861, 252786813629413,1255605670244016,6240630233618970, 31034662772521170,154411925525049741] |