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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 16 |
| 3 | 61 |
| 4 | 232 |
| 5 | 883 |
| 6 | 3361 |
| 7 | 12793 |
| 8 | 48694 |
| 9 | 185344 |
| 10 | 705475 |
| 11 | 2685250 |
| 12 | 10220869 |
| 13 | 38903701 |
| 14 | 148079185 |
| 15 | 563633908 |
| 16 | 2145360148 |
| 17 | 8165885869 |
| 18 | 31081817236 |
| 19 | 118306743223 |
| 20 | 450311041525 |
| 21 | 1714019240113 |
| 22 | 6524072662150 |
| 23 | 24832582450012 |
[4,16,61,232,883,3361,12793,48694,185344,705475, 2685250,10220869,38903701,148079185,563633908, 2145360148,8165885869,31081817236,118306743223, 450311041525,1714019240113,6524072662150, 24832582450012] |