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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 47 |
| 5 | 219 |
| 6 | 1081 |
| 7 | 5557 |
| 8 | 29439 |
| 9 | 159611 |
| 10 | 881405 |
| 11 | 4940385 |
| 12 | 28035205 |
| 13 | 160751005 |
| 14 | 929923395 |
| 15 | 5420717819 |
| 16 | 31809479855 |
| 17 | 187757573787 |
| 18 | 1114012352029 |
| 19 | 6640357243537 |
| 20 | 39746256802185 |
| 21 | 238796968208537 |
| 22 | 1439587364576015 |
[1,1,3,11,47,219,1081,5557,29439,159611,881405, 4940385,28035205,160751005,929923395,5420717819, 31809479855,187757573787,1114012352029, 6640357243537,39746256802185,238796968208537, 1439587364576015] |