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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 17 |
| 5 | 76 |
| 6 | 362 |
| 7 | 1842 |
| 8 | 9991 |
| 9 | 57568 |
| 10 | 351125 |
| 11 | 2259302 |
| 12 | 15288000 |
| 13 | 108478124 |
| 14 | 805037105 |
| 15 | 6233693772 |
| 16 | 50257390937 |
| 17 | 421049519856 |
| 18 | 3659097742426 |
| 19 | 32931956713294 |
| 20 | 306490813820239 |
| 21 | 2945638599347760 |
| 22 | 29198154161188501 |
[0,0,1,4,17,76,362,1842,9991,57568,351125,2259302, 15288000,108478124,805037105,6233693772, 50257390937,421049519856,3659097742426, 32931956713294,306490813820239,2945638599347760, 29198154161188501] |