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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 240 |
| 3 | 3402 |
| 4 | 32430 |
| 5 | 281350 |
| 6 | 2407152 |
| 7 | 19743140 |
| 8 | 158848594 |
| 9 | 1258624282 |
| 10 | 9844338028 |
| 11 | 76222734478 |
| 12 | 585218086730 |
| 13 | 4461176817796 |
| 14 | 33798763018094 |
| 15 | 254698642981228 |
| 16 | 1910389951978662 |
| 17 | 14270404594453084 |
| 18 | 106212957005378782 |
[0,240,3402,32430,281350,2407152,19743140, 158848594,1258624282,9844338028,76222734478, 585218086730,4461176817796,33798763018094, 254698642981228,1910389951978662, 14270404594453084,106212957005378782] |