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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 18 |
| 6 | 602 |
| 7 | 13198 |
| 8 | 258821 |
| 9 | 3339823 |
| 10 | 35591489 |
| 11 | 290017026 |
| 12 | 2017329742 |
| 13 | 11651785764 |
| 14 | 59635283471 |
| 15 | 266728654773 |
| 16 | 1087436395076 |
| 17 | 4003448283180 |
| 18 | 13715992117054 |
| 19 | 43384915194642 |
| 20 | 129627173525396 |
| 21 | 363261462194622 |
[0,0,0,1,18,602,13198,258821,3339823,35591489, 290017026,2017329742,11651785764,59635283471, 266728654773,1087436395076,4003448283180, 13715992117054,43384915194642,129627173525396, 363261462194622] |