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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 6726 |
| 4 | 51490 |
| 5 | 522538 |
| 6 | 2819011 |
| 7 | 15598126 |
| 8 | 66776089 |
| 9 | 278409356 |
| 10 | 1012789015 |
| 11 | 3553473100 |
| 12 | 11459870045 |
| 13 | 35680739958 |
| 14 | 104848228086 |
| 15 | 298518570528 |
| 16 | 814386983257 |
| 17 | 2161013972842 |
| 18 | 5546772124012 |
| 19 | 13896849891232 |
| 20 | 33892153400144 |
| 21 | 80925183641844 |
| 22 | 188938349276850 |
[1,0,0,6726,51490,522538,2819011,15598126, 66776089,278409356,1012789015,3553473100, 11459870045,35680739958,104848228086,298518570528, 814386983257,2161013972842,5546772124012, 13896849891232,33892153400144,80925183641844, 188938349276850] |