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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 11 |
| 4 | 54 |
| 5 | 202 |
| 6 | 671 |
| 7 | 2109 |
| 8 | 6460 |
| 9 | 19556 |
| 10 | 58893 |
| 11 | 176959 |
| 12 | 531218 |
| 13 | 1594062 |
| 14 | 4782667 |
| 15 | 14348561 |
| 16 | 43046328 |
| 17 | 129139720 |
| 18 | 387419993 |
| 19 | 1162260915 |
| 20 | 3486783790 |
| 21 | 10460352530 |
| 22 | 31381058871 |
| 23 | 94143178021 |
| 24 | 282429535604 |
| 25 | 847288608492 |
| 26 | 2541865827301 |
| 27 | 7625597483879 |
| 28 | 22876792453770 |
[0,0,1,11,54,202,671,2109,6460,19556,58893,176959, 531218,1594062,4782667,14348561,43046328, 129139720,387419993,1162260915,3486783790, 10460352530,31381058871,94143178021,282429535604, 847288608492,2541865827301,7625597483879, 22876792453770] |