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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 20 |
| 3 | 92 |
| 4 | 506 |
| 5 | 2288 |
| 6 | 10010 |
| 7 | 41618 |
| 8 | 168284 |
| 9 | 664958 |
| 10 | 2584442 |
| 11 | 9916688 |
| 12 | 37679618 |
| 13 | 142079906 |
| 14 | 532572428 |
| 15 | 1987037318 |
| 16 | 7386724082 |
| 17 | 27381500624 |
| 18 | 101272019258 |
| 19 | 373902595130 |
| 20 | 1378571667644 |
| 21 | 5077289249390 |
| 22 | 18683930010890 |
| 23 | 68709775705328 |
| 24 | 252549056389394 |
| 25 | 927895845621746 |
[1,1,20,92,506,2288,10010,41618,168284,664958, 2584442,9916688,37679618,142079906,532572428, 1987037318,7386724082,27381500624,101272019258, 373902595130,1378571667644,5077289249390, 18683930010890,68709775705328,252549056389394, 927895845621746] |