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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 15 |
| 3 | 87 |
| 4 | 519 |
| 5 | 3111 |
| 6 | 18663 |
| 7 | 111975 |
| 8 | 671847 |
| 9 | 4031079 |
| 10 | 24186471 |
| 11 | 145118823 |
| 12 | 870712935 |
| 13 | 5224277607 |
| 14 | 31345665639 |
| 15 | 188073993831 |
| 16 | 1128443962983 |
| 17 | 6770663777895 |
| 18 | 40623982667367 |
| 19 | 243743896004199 |
| 20 | 1462463376025191 |
| 21 | 8774780256151143 |
| 22 | 52648681536906855 |
| 23 | 315892089221441127 |
[1,3,15,87,519,3111,18663,111975,671847,4031079, 24186471,145118823,870712935,5224277607, 31345665639,188073993831,1128443962983, 6770663777895,40623982667367,243743896004199, 1462463376025191,8774780256151143, 52648681536906855,315892089221441127] |