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| n | a(n) |
|---|---|
| 0 | 55 |
| 1 | 220 |
| 2 | 1210 |
| 3 | 7942 |
| 4 | 57838 |
| 5 | 450670 |
| 6 | 3682030 |
| 7 | 31153342 |
| 8 | 270739678 |
| 9 | 2403012910 |
| 10 | 21693441550 |
| 11 | 198578979742 |
| 12 | 1838853136318 |
| 13 | 17193665419150 |
| 14 | 162090976108270 |
| 15 | 1538867288166142 |
| 16 | 14698448516729758 |
| 17 | 141129617123665390 |
| 18 | 1361277292619082190 |
[55,220,1210,7942,57838,450670,3682030,31153342, 270739678,2403012910,21693441550,198578979742, 1838853136318,17193665419150,162090976108270, 1538867288166142,14698448516729758, 141129617123665390,1361277292619082190] |