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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 20 |
| 3 | 470 |
| 4 | 19912 |
| 5 | 1326382 |
| 6 | 127677580 |
| 7 | 16767030632 |
| 8 | 2880746218304 |
| 9 | 627213971899610 |
| 10 | 168767535712912684 |
| 11 | 54994347890521005100 |
| 12 | 21342142821229037730064 |
| 13 | 9726400286221416303901358 |
| 14 | 5143644030714149522751534524 |
| 15 | 3124088412968372614077895431788 |
| 16 | 2159818183532141245447039295746240 |
| 17 | 1686295004858842334963772859214802354 |
| 18 | 1476540037893212558044217633785452773068 |
| 19 | 1440964034588041764141738802548853847618732 |
[1,2,20,470,19912,1326382,127677580,16767030632, 2880746218304,627213971899610,168767535712912684, 54994347890521005100,21342142821229037730064, 9726400286221416303901358, 5143644030714149522751534524, 3124088412968372614077895431788, 2159818183532141245447039295746240, 1686295004858842334963772859214802354, 1476540037893212558044217633785452773068, 1440964034588041764141738802548853847618732] |