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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 27 |
| 3 | 98 |
| 4 | 315 |
| 5 | 918 |
| 6 | 2491 |
| 7 | 6366 |
| 8 | 15498 |
| 9 | 36182 |
| 10 | 81501 |
| 11 | 177876 |
| 12 | 377558 |
| 13 | 781626 |
| 14 | 1582173 |
| 15 | 3137832 |
| 16 | 6108051 |
| 17 | 11687598 |
| 18 | 22012816 |
| 19 | 40855674 |
| 20 | 74799828 |
| 21 | 135210868 |
| 22 | 241511115 |
| 23 | 426570624 |
| 24 | 745516240 |
| 25 | 1290006276 |
| 26 | 2211202692 |
| 27 | 3756468658 |
| 28 | 6327617862 |
| 29 | 10572763842 |
[1,6,27,98,315,918,2491,6366,15498,36182,81501, 177876,377558,781626,1582173,3137832,6108051, 11687598,22012816,40855674,74799828,135210868, 241511115,426570624,745516240,1290006276, 2211202692,3756468658,6327617862,10572763842] |