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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 28 |
| 2 | 406 |
| 3 | 4631 |
| 4 | 38304 |
| 5 | 249814 |
| 6 | 1357051 |
| 7 | 6362806 |
| 8 | 26400811 |
| 9 | 98755951 |
| 10 | 337852708 |
| 11 | 1069253171 |
| 12 | 3159851197 |
| 13 | 8786784471 |
| 14 | 23140533785 |
| 15 | 58032604728 |
| 16 | 139238130793 |
| 17 | 320911139366 |
| 18 | 712976624945 |
| 19 | 1531659348507 |
| 20 | 3190199728577 |
| 21 | 6457722870812 |
| 22 | 12731177730290 |
| 23 | 24491108899982 |
[1,28,406,4631,38304,249814,1357051,6362806, 26400811,98755951,337852708,1069253171,3159851197, 8786784471,23140533785,58032604728,139238130793, 320911139366,712976624945,1531659348507, 3190199728577,6457722870812,12731177730290, 24491108899982] |