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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 7 |
| 6 | 40 |
| 7 | 236 |
| 8 | 1876 |
| 9 | 9948 |
| 10 | 147880 |
| 11 | 1453960 |
| 12 | 22015900 |
| 13 | 208197540 |
| 14 | 4313645260 |
| 15 | 50025596492 |
| 16 | 908013578304 |
| 17 | 10257540119128 |
| 18 | 410662921858728 |
| 19 | 7157148265575464 |
| 20 | 196798065310375948 |
| 21 | 3119117728942974484 |
| 22 | 117123479632632724204 |
| 23 | 2164788189493906776364 |
| 24 | 62917262965957689991564 |
| 25 | 1107373183582759036993164 |
| 26 | 59647207431378288643241916 |
| 27 | 1329593013280581859290571836 |
| 28 | 48482067282133360326936987936 |
[1,1,3,7,40,236,1876,9948,147880,1453960,22015900, 208197540,4313645260,50025596492,908013578304, 10257540119128,410662921858728,7157148265575464, 196798065310375948,3119117728942974484, 117123479632632724204,2164788189493906776364, 62917262965957689991564,1107373183582759036993164, 59647207431378288643241916, 1329593013280581859290571836, 48482067282133360326936987936] |