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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 3 |
| 2 | 9 |
| 3 | 22 |
| 4 | 51 |
| 5 | 114 |
| 6 | 250 |
| 7 | 540 |
| 8 | 1155 |
| 9 | 2450 |
| 10 | 5166 |
| 11 | 10836 |
| 12 | 22638 |
| 13 | 47124 |
| 14 | 97812 |
| 15 | 202488 |
| 16 | 418275 |
| 17 | 862290 |
| 18 | 1774630 |
| 19 | 3646500 |
| 20 | 7482618 |
| 21 | 15334748 |
| 22 | 31391724 |
| 23 | 64194312 |
| 24 | 131151566 |
| 25 | 267711444 |
| 26 | 546031500 |
| 27 | 1112864200 |
| 28 | 2266587900 |
| 29 | 4613409000 |
| 30 | 9384609960 |
| 31 | 19079454960 |
[0,3,9,22,51,114,250,540,1155,2450,5166,10836, 22638,47124,97812,202488,418275,862290,1774630, 3646500,7482618,15334748,31391724,64194312, 131151566,267711444,546031500,1112864200, 2266587900,4613409000,9384609960,19079454960] |