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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 16 |
| 3 | 95 |
| 4 | 635 |
| 5 | 4534 |
| 6 | 33890 |
| 7 | 261765 |
| 8 | 2072641 |
| 9 | 16732801 |
| 10 | 137213748 |
| 11 | 1139738646 |
| 12 | 9569342309 |
| 13 | 81082064798 |
| 14 | 692433744780 |
| 15 | 5953828761669 |
| 16 | 51500965421571 |
| 17 | 447852196503417 |
| 18 | 3912938946491980 |
| 19 | 34332723663216311 |
| 20 | 302391399344255051 |
| 21 | 2672583238541562604 |
[1,3,16,95,635,4534,33890,261765,2072641,16732801, 137213748,1139738646,9569342309,81082064798, 692433744780,5953828761669,51500965421571, 447852196503417,3912938946491980, 34332723663216311,302391399344255051, 2672583238541562604] |