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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 9 |
| 4 | 22 |
| 5 | 56 |
| 6 | 148 |
| 7 | 402 |
| 8 | 1112 |
| 9 | 3118 |
| 10 | 8832 |
| 11 | 25205 |
| 12 | 72342 |
| 13 | 208560 |
| 14 | 603404 |
| 15 | 1750785 |
| 16 | 5092046 |
| 17 | 14839710 |
| 18 | 43321976 |
| 19 | 126661355 |
| 20 | 370813762 |
| 21 | 1086877792 |
| 22 | 3189091724 |
| 23 | 9366371000 |
| 24 | 27533212140 |
| 25 | 81001276874 |
| 26 | 238478223648 |
| 27 | 702592110803 |
| 28 | 2071257446234 |
| 29 | 6109731270056 |
[1,2,4,9,22,56,148,402,1112,3118,8832,25205,72342, 208560,603404,1750785,5092046,14839710,43321976, 126661355,370813762,1086877792,3189091724, 9366371000,27533212140,81001276874,238478223648, 702592110803,2071257446234,6109731270056] |