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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 55 |
| 4 | 478 |
| 5 | 2166 |
| 6 | 7120 |
| 7 | 19219 |
| 8 | 45316 |
| 9 | 96732 |
| 10 | 191232 |
| 11 | 355575 |
| 12 | 628738 |
| 13 | 1065922 |
| 14 | 1743456 |
| 15 | 2764723 |
| 16 | 4267240 |
| 17 | 6431032 |
| 18 | 9488448 |
| 19 | 13735575 |
| 20 | 19545414 |
| 21 | 27382990 |
| 22 | 37822576 |
| 23 | 51567219 |
| 24 | 69470764 |
| 25 | 92562580 |
| 26 | 122075200 |
[0,0,55,478,2166,7120,19219,45316,96732,191232, 355575,628738,1065922,1743456,2764723,4267240, 6431032,9488448,13735575,19545414,27382990, 37822576,51567219,69470764,92562580,122075200] |