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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 6 |
| 5 | 26 |
| 6 | 49 |
| 7 | 154 |
| 8 | 258 |
| 9 | 666 |
| 10 | 2404 |
| 11 | 3588 |
| 12 | 11096 |
| 13 | 22477 |
| 14 | 31620 |
| 15 | 61247 |
| 16 | 157725 |
| 17 | 387527 |
| 18 | 518155 |
| 19 | 1208470 |
| 20 | 2086019 |
| 21 | 2726745 |
| 22 | 5975695 |
| 23 | 9935799 |
| 24 | 20882243 |
| 25 | 54355088 |
| 26 | 86547260 |
| 27 | 108874661 |
| 28 | 171286370 |
| 29 | 214236058 |
| 30 | 333331046 |
| 31 | 1486031972 |
| 32 | 2246585402 |
| 33 | 4132451733 |
[0,0,2,6,26,49,154,258,666,2404,3588,11096,22477, 31620,61247,157725,387527,518155,1208470,2086019, 2726745,5975695,9935799,20882243,54355088, 86547260,108874661,171286370,214236058,333331046, 1486031972,2246585402,4132451733] |