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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 7 |
| 4 | 25 |
| 5 | 92 |
| 6 | 403 |
| 7 | 1710 |
| 8 | 8021 |
| 9 | 36160 |
| 10 | 175685 |
| 11 | 811796 |
| 12 | 3996105 |
| 13 | 18729552 |
| 14 | 92602363 |
| 15 | 438528764 |
| 16 | 2169839823 |
| 17 | 10361611742 |
| 18 | 51246105785 |
| 19 | 246397237188 |
| 20 | 1217744328605 |
| 21 | 5887982752143 |
| 22 | 29081428391143 |
| 23 | 141255777787573 |
| 24 | 697390129303759 |
[2,4,7,25,92,403,1710,8021,36160,175685,811796, 3996105,18729552,92602363,438528764,2169839823, 10361611742,51246105785,246397237188, 1217744328605,5887982752143,29081428391143, 141255777787573,697390129303759] |