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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 23 |
| 4 | 106 |
| 5 | 576 |
| 6 | 3622 |
| 7 | 26006 |
| 8 | 210828 |
| 9 | 1910096 |
| 10 | 19162096 |
| 11 | 211095732 |
| 12 | 2534829376 |
| 13 | 32962249568 |
| 14 | 461527198056 |
| 15 | 6923249156336 |
| 16 | 110774157354832 |
| 17 | 1883174989346016 |
| 18 | 33897247428278368 |
| 19 | 644048388555567536 |
| 20 | 12880972761058252896 |
| 21 | 270500465268345299072 |
| 22 | 5951010522336442007776 |
| 23 | 136873244273143429751328 |
[1,2,6,23,106,576,3622,26006,210828,1910096, 19162096,211095732,2534829376,32962249568, 461527198056,6923249156336,110774157354832, 1883174989346016,33897247428278368, 644048388555567536,12880972761058252896, 270500465268345299072,5951010522336442007776, 136873244273143429751328] |