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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 61 |
| 5 | 540 |
| 6 | 5879 |
| 7 | 75887 |
| 8 | 1132426 |
| 9 | 19175355 |
| 10 | 363199319 |
| 11 | 7608010344 |
| 12 | 174621038593 |
| 13 | 4357917954481 |
| 14 | 117489163732394 |
| 15 | 3402827830284945 |
| 16 | 105370173575100901 |
| 17 | 3473812900148044788 |
| 18 | 121478081331606466679 |
| 19 | 4491215196369291222335 |
| 20 | 175035914577070751204386 |
[1,1,2,9,61,540,5879,75887,1132426,19175355, 363199319,7608010344,174621038593,4357917954481, 117489163732394,3402827830284945, 105370173575100901,3473812900148044788, 121478081331606466679,4491215196369291222335, 175035914577070751204386] |