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| n | a(n) |
|---|---|
| 1 | 90 |
| 2 | 370 |
| 3 | 1640 |
| 4 | 7554 |
| 5 | 35072 |
| 6 | 163416 |
| 7 | 762002 |
| 8 | 3554334 |
| 9 | 16580250 |
| 10 | 77345792 |
| 11 | 360815494 |
| 12 | 1683196556 |
| 13 | 7852080772 |
| 14 | 36629820538 |
| 15 | 170877487282 |
| 16 | 797140579074 |
| 17 | 3718647299872 |
| 18 | 17347426713674 |
| 19 | 80925452066672 |
| 20 | 377515864606272 |
[90,370,1640,7554,35072,163416,762002,3554334, 16580250,77345792,360815494,1683196556,7852080772, 36629820538,170877487282,797140579074, 3718647299872,17347426713674,80925452066672, 377515864606272] |