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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 36 |
| 4 | 168 |
| 5 | 720 |
| 6 | 3304 |
| 7 | 15088 |
| 8 | 69904 |
| 9 | 326624 |
| 10 | 1535040 |
| 11 | 7251968 |
| 12 | 34448064 |
| 13 | 164071424 |
| 14 | 784830976 |
| 15 | 3762710272 |
| 16 | 18090215424 |
| 17 | 87167033856 |
| 18 | 420815500544 |
| 19 | 2035432822272 |
| 20 | 9860443239424 |
| 21 | 47839254740992 |
| 22 | 232412062604288 |
| 23 | 1130458029407232 |
| 24 | 5504894214334464 |
| 25 | 26834127921946624 |
| 26 | 130931569849067520 |
[1,2,10,36,168,720,3304,15088,69904,326624, 1535040,7251968,34448064,164071424,784830976, 3762710272,18090215424,87167033856,420815500544, 2035432822272,9860443239424,47839254740992, 232412062604288,1130458029407232,5504894214334464, 26834127921946624,130931569849067520] |