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| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 65 |
| 3 | 192 |
| 4 | 581 |
| 5 | 1733 |
| 6 | 5216 |
| 7 | 15613 |
| 8 | 46897 |
| 9 | 140568 |
| 10 | 421901 |
| 11 | 1265269 |
| 12 | 3796472 |
| 13 | 11387877 |
| 14 | 34165857 |
| 15 | 102492080 |
| 16 | 307483605 |
| 17 | 922431077 |
| 18 | 2767317200 |
| 19 | 8301880013 |
| 20 | 24905716177 |
| 21 | 74716886152 |
| 22 | 224150891421 |
| 23 | 672451700885 |
| 24 | 2017355772136 |
[21,65,192,581,1733,5216,15613,46897,140568, 421901,1265269,3796472,11387877,34165857, 102492080,307483605,922431077,2767317200, 8301880013,24905716177,74716886152,224150891421, 672451700885,2017355772136] |