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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 13 |
| 5 | 59 |
| 6 | 336 |
| 7 | 2245 |
| 8 | 17408 |
| 9 | 153124 |
| 10 | 1505420 |
| 11 | 16342711 |
| 12 | 194060616 |
| 13 | 2501178199 |
| 14 | 34766184181 |
| 15 | 518332353130 |
| 16 | 8250146291076 |
| 17 | 139618375340912 |
| 18 | 2503167665128431 |
| 19 | 47393482639721484 |
| 20 | 944910760664087791 |
| 21 | 19787603213440946946 |
| 22 | 434229133448518143203 |
[1,0,1,3,13,59,336,2245,17408,153124,1505420, 16342711,194060616,2501178199,34766184181, 518332353130,8250146291076,139618375340912, 2503167665128431,47393482639721484, 944910760664087791,19787603213440946946, 434229133448518143203] |