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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 11 |
| 6 | 42 |
| 7 | 196 |
| 8 | 988 |
| 9 | 5314 |
| 10 | 30724 |
| 11 | 189962 |
| 12 | 1244264 |
| 13 | 8583042 |
| 14 | 62112639 |
| 15 | 469917193 |
| 16 | 3707053139 |
| 17 | 30421506639 |
| 18 | 259182853643 |
| 19 | 2288352779166 |
| 20 | 20904648990227 |
| 21 | 197305045507448 |
| 22 | 1921509079008868 |
| 23 | 19285642292478101 |
[1,1,1,4,11,42,196,988,5314,30724,189962,1244264, 8583042,62112639,469917193,3707053139,30421506639, 259182853643,2288352779166,20904648990227, 197305045507448,1921509079008868, 19285642292478101] |