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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 17 |
| 6 | 57 |
| 7 | 233 |
| 8 | 989 |
| 9 | 4602 |
| 10 | 23794 |
| 11 | 129285 |
| 12 | 751973 |
| 13 | 4680041 |
| 14 | 30523105 |
| 15 | 210159654 |
| 16 | 1521122754 |
| 17 | 11481486845 |
| 18 | 90604333205 |
| 19 | 744420806913 |
| 20 | 6348340033789 |
| 21 | 56202980961206 |
| 22 | 514994183598470 |
| 23 | 4877587872447801 |
| 24 | 47711923353493817 |
| 25 | 481072714151555073 |
| 26 | 4995769099914083313 |
[1,1,2,6,17,57,233,989,4602,23794,129285,751973, 4680041,30523105,210159654,1521122754,11481486845, 90604333205,744420806913,6348340033789, 56202980961206,514994183598470,4877587872447801, 47711923353493817,481072714151555073, 4995769099914083313] |