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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 17 |
| 2 | 75 |
| 3 | 333 |
| 4 | 1481 |
| 5 | 6589 |
| 6 | 29317 |
| 7 | 130445 |
| 8 | 580413 |
| 9 | 2582541 |
| 10 | 11490989 |
| 11 | 51129037 |
| 12 | 227498125 |
| 13 | 1012250573 |
| 14 | 4503998541 |
| 15 | 20040495309 |
| 16 | 89169978317 |
| 17 | 396760903885 |
| 18 | 1765383572173 |
| 19 | 7855056096461 |
| 20 | 34950991530189 |
| 21 | 155514078313677 |
| 22 | 691958296315085 |
| 23 | 3078861341887693 |
[4,17,75,333,1481,6589,29317,130445,580413, 2582541,11490989,51129037,227498125,1012250573, 4503998541,20040495309,89169978317,396760903885, 1765383572173,7855056096461,34950991530189, 155514078313677,691958296315085,3078861341887693] |