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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 49 |
| 5 | 197 |
| 6 | 812 |
| 7 | 3474 |
| 8 | 15158 |
| 9 | 67376 |
| 10 | 303459 |
| 11 | 1383358 |
| 12 | 6363572 |
| 13 | 29509269 |
| 14 | 137771543 |
| 15 | 646907907 |
| 16 | 3052952032 |
| 17 | 14470721920 |
| 18 | 68854163470 |
| 19 | 328735177885 |
| 20 | 1574256833505 |
| 21 | 7559227173640 |
| 22 | 36385912226315 |
| 23 | 175525189436472 |
| 24 | 848409828992201 |
| 25 | 4108222390467437 |
| 26 | 19925762711434817 |
| 27 | 96789429703804583 |
[1,1,4,13,49,197,812,3474,15158,67376,303459, 1383358,6363572,29509269,137771543,646907907, 3052952032,14470721920,68854163470,328735177885, 1574256833505,7559227173640,36385912226315, 175525189436472,848409828992201,4108222390467437, 19925762711434817,96789429703804583] |