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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 16 |
| 3 | 62 |
| 4 | 242 |
| 5 | 950 |
| 6 | 3744 |
| 7 | 14802 |
| 8 | 58662 |
| 9 | 232916 |
| 10 | 926120 |
| 11 | 3628422 |
| 12 | 14381528 |
| 13 | 57148222 |
| 14 | 227453736 |
| 15 | 906239638 |
| 16 | 3576510068 |
| 17 | 14222021944 |
| 18 | 56647350200 |
| 19 | 225861048608 |
| 20 | 901148151936 |
| 21 | 3573218491998 |
| 22 | 14238032956598 |
| 23 | 56794010648340 |
[4,16,62,242,950,3744,14802,58662,232916,926120, 3628422,14381528,57148222,227453736,906239638, 3576510068,14222021944,56647350200,225861048608, 901148151936,3573218491998,14238032956598, 56794010648340] |