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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 220 |
| 2 | 9482 |
| 3 | 166188 |
| 4 | 1660450 |
| 5 | 11260876 |
| 6 | 57581898 |
| 7 | 237782204 |
| 8 | 831240322 |
| 9 | 2543995388 |
| 10 | 6986455498 |
| 11 | 17539148684 |
| 12 | 40829208354 |
| 13 | 89125931884 |
| 14 | 184069213834 |
| 15 | 362272019868 |
| 16 | 683489419778 |
| 17 | 1242224123932 |
| 18 | 2183844052874 |
| 19 | 3726523300588 |
| 20 | 6190586013986 |
| 21 | 10037135290380 |
[1,220,9482,166188,1660450,11260876,57581898, 237782204,831240322,2543995388,6986455498, 17539148684,40829208354,89125931884,184069213834, 362272019868,683489419778,1242224123932, 2183844052874,3726523300588,6190586013986, 10037135290380] |