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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 39 |
| 5 | 118 |
| 6 | 371 |
| 7 | 1129 |
| 8 | 3468 |
| 9 | 10524 |
| 10 | 31910 |
| 11 | 96155 |
| 12 | 289016 |
| 13 | 865000 |
| 14 | 2581577 |
| 15 | 7679762 |
| 16 | 22784896 |
| 17 | 67418329 |
| 18 | 199004329 |
| 19 | 586052299 |
| 20 | 1722165404 |
| 21 | 5050349249 |
| 22 | 14781877481 |
| 23 | 43185726143 |
| 24 | 125949155473 |
| 25 | 366716549379 |
| 26 | 1066057177765 |
| 27 | 3094398005409 |
| 28 | 8969054893842 |
[1,1,4,12,39,118,371,1129,3468,10524,31910,96155, 289016,865000,2581577,7679762,22784896,67418329, 199004329,586052299,1722165404,5050349249, 14781877481,43185726143,125949155473,366716549379, 1066057177765,3094398005409,8969054893842] |