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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 7 |
| 2 | 35 |
| 3 | 217 |
| 4 | 1295 |
| 5 | 7777 |
| 6 | 46655 |
| 7 | 279937 |
| 8 | 1679615 |
| 9 | 10077697 |
| 10 | 60466175 |
| 11 | 362797057 |
| 12 | 2176782335 |
| 13 | 13060694017 |
| 14 | 78364164095 |
| 15 | 470184984577 |
| 16 | 2821109907455 |
| 17 | 16926659444737 |
| 18 | 101559956668415 |
| 19 | 609359740010497 |
| 20 | 3656158440062975 |
| 21 | 21936950640377857 |
| 22 | 131621703842267135 |
[0,7,35,217,1295,7777,46655,279937,1679615, 10077697,60466175,362797057,2176782335, 13060694017,78364164095,470184984577, 2821109907455,16926659444737,101559956668415, 609359740010497,3656158440062975, 21936950640377857,131621703842267135] |