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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 10 |
| 3 | 68 |
| 4 | 394 |
| 5 | 2092 |
| 6 | 10516 |
| 7 | 50920 |
| 8 | 239962 |
| 9 | 1107836 |
| 10 | 5033020 |
| 11 | 22572376 |
| 12 | 100168260 |
| 13 | 440604088 |
| 14 | 1923626344 |
| 15 | 8344694224 |
| 16 | 35998921978 |
| 17 | 154546983580 |
| 18 | 660652406572 |
| 19 | 2813422792696 |
| 20 | 11940478362796 |
| 21 | 50522190460072 |
[1,10,68,394,2092,10516,50920,239962,1107836, 5033020,22572376,100168260,440604088,1923626344, 8344694224,35998921978,154546983580,660652406572, 2813422792696,11940478362796,50522190460072] |