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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 45 |
| 5 | 216 |
| 6 | 1232 |
| 7 | 7624 |
| 8 | 52215 |
| 9 | 385495 |
| 10 | 3056680 |
| 11 | 25825669 |
| 12 | 231503636 |
| 13 | 2191866327 |
| 14 | 21835650219 |
| 15 | 228089127908 |
| 16 | 2490775088645 |
| 17 | 28362322146780 |
| 18 | 336015253520857 |
| 19 | 4133561828779865 |
| 20 | 52705520063966840 |
| 21 | 695406327616587268 |
| 22 | 9480212057583970983 |
[1,1,3,10,45,216,1232,7624,52215,385495,3056680, 25825669,231503636,2191866327,21835650219, 228089127908,2490775088645,28362322146780, 336015253520857,4133561828779865, 52705520063966840,695406327616587268, 9480212057583970983] |