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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 30 |
| 4 | 144 |
| 5 | 741 |
| 6 | 3996 |
| 7 | 22287 |
| 8 | 127494 |
| 9 | 743919 |
| 10 | 4410255 |
| 11 | 26489073 |
| 12 | 160843708 |
| 13 | 985729010 |
| 14 | 6089215057 |
| 15 | 37875775533 |
| 16 | 237021929322 |
| 17 | 1491204370335 |
| 18 | 9426547131330 |
| 19 | 59843910602283 |
| 20 | 381378377720469 |
| 21 | 2438954925930558 |
| 22 | 15646857920046108 |
[1,2,7,30,144,741,3996,22287,127494,743919, 4410255,26489073,160843708,985729010,6089215057, 37875775533,237021929322,1491204370335, 9426547131330,59843910602283,381378377720469, 2438954925930558,15646857920046108] |