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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 42 |
| 5 | 162 |
| 6 | 634 |
| 7 | 2726 |
| 8 | 9330 |
| 9 | 37814 |
| 10 | 186034 |
| 11 | 623934 |
| 12 | 2370354 |
| 13 | 10505738 |
| 14 | 37417658 |
| 15 | 113248562 |
| 16 | 738713250 |
| 17 | 2753640290 |
| 18 | 7522970666 |
| 19 | 46292418830 |
| 20 | 146514514914 |
| 21 | 496491671978 |
| 22 | 2915741154442 |
| 23 | 9464309679414 |
| 24 | 39098814277474 |
| 25 | 173211426442282 |
| 26 | 652232674100690 |
[1,1,2,6,42,162,634,2726,9330,37814,186034,623934, 2370354,10505738,37417658,113248562,738713250, 2753640290,7522970666,46292418830,146514514914, 496491671978,2915741154442,9464309679414, 39098814277474,173211426442282,652232674100690] |