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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 27 |
| 3 | 155 |
| 4 | 931 |
| 5 | 5775 |
| 6 | 36645 |
| 7 | 236325 |
| 8 | 1542195 |
| 9 | 10153775 |
| 10 | 67313377 |
| 11 | 448691985 |
| 12 | 3004182349 |
| 13 | 20188647185 |
| 14 | 136094684907 |
| 15 | 919884469275 |
| 16 | 6232016686995 |
| 17 | 42305974804575 |
| 18 | 287706424085745 |
| 19 | 1959685788407025 |
| 20 | 13367193276457881 |
| 21 | 91295551930615005 |
| 22 | 624255065007468207 |
[1,5,27,155,931,5775,36645,236325,1542195, 10153775,67313377,448691985,3004182349, 20188647185,136094684907,919884469275, 6232016686995,42305974804575,287706424085745, 1959685788407025,13367193276457881, 91295551930615005,624255065007468207] |