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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 5 |
| 4 | 6 |
| 5 | 33 |
| 6 | 72 |
| 7 | 261 |
| 8 | 702 |
| 9 | 2241 |
| 10 | 6480 |
| 11 | 19845 |
| 12 | 58806 |
| 13 | 177633 |
| 14 | 530712 |
| 15 | 1595781 |
| 16 | 4780782 |
| 17 | 14353281 |
| 18 | 43040160 |
| 19 | 129153285 |
| 20 | 387400806 |
| 21 | 1162300833 |
| 22 | 3486725352 |
| 23 | 10460471301 |
| 24 | 31380882462 |
| 25 | 94143533121 |
| 26 | 282429005040 |
| 27 | 847289672325 |
| 28 | 2541864234006 |
| 29 | 7625600673633 |
[1,0,5,6,33,72,261,702,2241,6480,19845,58806, 177633,530712,1595781,4780782,14353281,43040160, 129153285,387400806,1162300833,3486725352, 10460471301,31380882462,94143533121,282429005040, 847289672325,2541864234006,7625600673633] |