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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 15 |
| 3 | 71 |
| 4 | 299 |
| 5 | 1325 |
| 6 | 5845 |
| 7 | 25785 |
| 8 | 113841 |
| 9 | 502523 |
| 10 | 2218399 |
| 11 | 9793287 |
| 12 | 43233099 |
| 13 | 190855613 |
| 14 | 842545925 |
| 15 | 3719480233 |
| 16 | 16419916497 |
| 17 | 72486917979 |
| 18 | 319998782959 |
| 19 | 1412657953559 |
| 20 | 6236281512443 |
| 21 | 27530519336653 |
| 22 | 121535484480133 |
[3,15,71,299,1325,5845,25785,113841,502523, 2218399,9793287,43233099,190855613,842545925, 3719480233,16419916497,72486917979,319998782959, 1412657953559,6236281512443,27530519336653, 121535484480133] |