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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 38 |
| 3 | 395 |
| 4 | 3778 |
| 5 | 32178 |
| 6 | 261356 |
| 7 | 2096110 |
| 8 | 16776148 |
| 9 | 134216342 |
| 10 | 1073740504 |
| 11 | 8589932829 |
| 12 | 68719475152 |
| 13 | 549755811711 |
| 14 | 4398046509244 |
| 15 | 35184372086204 |
| 16 | 281474976708508 |
| 17 | 2251799813682132 |
| 18 | 18014398509479536 |
| 19 | 144115188075852231 |
[4,38,395,3778,32178,261356,2096110,16776148, 134216342,1073740504,8589932829,68719475152, 549755811711,4398046509244,35184372086204, 281474976708508,2251799813682132, 18014398509479536,144115188075852231] |