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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 31 |
| 6 | 337 |
| 7 | 2570 |
| 8 | 16865 |
| 9 | 104858 |
| 10 | 650761 |
| 11 | 4145956 |
| 12 | 27483392 |
| 13 | 190522216 |
| 14 | 1382087111 |
| 15 | 10478149999 |
| 16 | 82860356456 |
| 17 | 682066659044 |
| 18 | 5832719543338 |
| 19 | 51724107920729 |
| 20 | 474869705028520 |
| 21 | 4506715494154371 |
| 22 | 44152005320340946 |
[1,31,337,2570,16865,104858,650761,4145956, 27483392,190522216,1382087111,10478149999, 82860356456,682066659044,5832719543338, 51724107920729,474869705028520,4506715494154371, 44152005320340946] |