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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 73 |
| 3 | 511 |
| 4 | 3577 |
| 5 | 37303 |
| 6 | 262657 |
| 7 | 1838599 |
| 8 | 19173961 |
| 9 | 134217727 |
| 10 | 939524089 |
| 11 | 9797894071 |
| 12 | 68585258497 |
| 13 | 480096809479 |
| 14 | 5006723870281 |
| 15 | 35253225520639 |
| 16 | 246772578644473 |
| 17 | 2573485463006647 |
| 18 | 18014398643699713 |
| 19 | 126100790505897991 |
[1,7,73,511,3577,37303,262657,1838599,19173961, 134217727,939524089,9797894071,68585258497, 480096809479,5006723870281,35253225520639, 246772578644473,2573485463006647, 18014398643699713,126100790505897991] |