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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 33 |
| 5 | 191 |
| 6 | 1323 |
| 7 | 10711 |
| 8 | 99151 |
| 9 | 1032385 |
| 10 | 11943003 |
| 11 | 151979213 |
| 12 | 2109829857 |
| 13 | 31730171539 |
| 14 | 513903517585 |
| 15 | 8917723105003 |
| 16 | 165065061436755 |
| 17 | 3246274767649637 |
| 18 | 67598797715175999 |
| 19 | 1485845872704318265 |
| 20 | 34378343609138619685 |
| 21 | 835190283258080561671 |
[1,1,2,7,33,191,1323,10711,99151,1032385,11943003, 151979213,2109829857,31730171539,513903517585, 8917723105003,165065061436755,3246274767649637, 67598797715175999,1485845872704318265, 34378343609138619685,835190283258080561671] |