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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 31 |
| 4 | 171 |
| 5 | 921 |
| 6 | 5031 |
| 7 | 27281 |
| 8 | 148101 |
| 9 | 801901 |
| 10 | 4336902 |
| 11 | 23415777 |
| 12 | 126254962 |
| 13 | 679805112 |
| 14 | 3655679442 |
| 15 | 19634501447 |
| 16 | 105334380517 |
| 17 | 564471596667 |
| 18 | 3021754455157 |
| 19 | 16160029793032 |
| 20 | 86339725851558 |
| 21 | 460874548444683 |
| 22 | 2457961986888773 |
| 23 | 13097958657023523 |
| 24 | 69740119667456018 |
[1,1,6,31,171,921,5031,27281,148101,801901, 4336902,23415777,126254962,679805112,3655679442, 19634501447,105334380517,564471596667, 3021754455157,16160029793032,86339725851558, 460874548444683,2457961986888773, 13097958657023523,69740119667456018] |