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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 2 |
| 3 | 14 |
| 4 | 18 |
| 5 | 62 |
| 6 | 1046 |
| 7 | 1934 |
| 8 | 7538 |
| 9 | 33278 |
| 10 | 1290822 |
| 11 | 2916014 |
| 12 | 14298246 |
| 13 | 64274862 |
| 14 | 430953854 |
| 15 | 30305249534 |
| 16 | 83399665778 |
| 17 | 474765871742 |
| 18 | 2411716115558 |
| 19 | 15781599222830 |
| 20 | 127858161797078 |
| 21 | 16263964079638478 |
[1,2,2,14,18,62,1046,1934,7538,33278,1290822, 2916014,14298246,64274862,430953854,30305249534, 83399665778,474765871742,2411716115558, 15781599222830,127858161797078,16263964079638478] |