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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 31 |
| 4 | 141 |
| 5 | 631 |
| 6 | 2773 |
| 7 | 12013 |
| 8 | 51481 |
| 9 | 218791 |
| 10 | 923781 |
| 11 | 3879877 |
| 12 | 16224937 |
| 13 | 67603901 |
| 14 | 280816201 |
| 15 | 1163381401 |
| 16 | 4808643121 |
| 17 | 19835652871 |
| 18 | 81676217701 |
| 19 | 335780006101 |
| 20 | 1378465288201 |
| 21 | 5651707681621 |
| 22 | 23145088600921 |
| 23 | 94684453367401 |
| 24 | 386971244197201 |
| 25 | 1580132580471901 |
[1,2,7,31,141,631,2773,12013,51481,218791,923781, 3879877,16224937,67603901,280816201,1163381401, 4808643121,19835652871,81676217701,335780006101, 1378465288201,5651707681621,23145088600921, 94684453367401,386971244197201,1580132580471901] |