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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 8 |
| 4 | 22 |
| 5 | 121 |
| 6 | 406 |
| 7 | 2155 |
| 8 | 7624 |
| 9 | 40717 |
| 10 | 147001 |
| 11 | 792351 |
| 12 | 2892044 |
| 13 | 15703156 |
| 14 | 57728737 |
| 15 | 315180458 |
| 16 | 1164727748 |
| 17 | 6385672193 |
| 18 | 23691834033 |
| 19 | 130316812494 |
| 20 | 485018155062 |
| 21 | 2674846358141 |
| 22 | 9980763478121 |
| 23 | 55161813337474 |
| 24 | 206262229900060 |
| 25 | 1142020843590221 |
| 26 | 4277853480389546 |
| 27 | 23721423518350124 |
| 28 | 88991782850212510 |
[1,1,8,22,121,406,2155,7624,40717,147001,792351, 2892044,15703156,57728737,315180458,1164727748, 6385672193,23691834033,130316812494,485018155062, 2674846358141,9980763478121,55161813337474, 206262229900060,1142020843590221,4277853480389546, 23721423518350124,88991782850212510] |