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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 244 |
| 6 | 6480 |
| 7 | 69798 |
| 8 | 496198 |
| 9 | 2595897 |
| 10 | 10912452 |
| 11 | 38739354 |
| 12 | 121694240 |
| 13 | 342722071 |
| 14 | 887407361 |
| 15 | 2136513884 |
| 16 | 4828507719 |
| 17 | 10332712952 |
| 18 | 21117591802 |
| 19 | 41392701372 |
| 20 | 78248425161 |
| 21 | 143087468105 |
| 22 | 253946607496 |
| 23 | 438734862156 |
[0,0,0,1,244,6480,69798,496198,2595897,10912452, 38739354,121694240,342722071,887407361,2136513884, 4828507719,10332712952,21117591802,41392701372, 78248425161,143087468105,253946607496, 438734862156] |