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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 8 |
| 3 | 42 |
| 4 | 200 |
| 5 | 910 |
| 6 | 4032 |
| 7 | 17556 |
| 8 | 75504 |
| 9 | 321750 |
| 10 | 1361360 |
| 11 | 5727436 |
| 12 | 23984688 |
| 13 | 100053772 |
| 14 | 416024000 |
| 15 | 1725013800 |
| 16 | 7135405920 |
| 17 | 29452939110 |
| 18 | 121347523440 |
| 19 | 499132441500 |
| 20 | 2050025300400 |
| 21 | 8408638258020 |
| 22 | 34448503964160 |
| 23 | 140974630569240 |
| 24 | 576340150932000 |
| 25 | 2354075068866300 |
[1,8,42,200,910,4032,17556,75504,321750,1361360, 5727436,23984688,100053772,416024000,1725013800, 7135405920,29452939110,121347523440,499132441500, 2050025300400,8408638258020,34448503964160, 140974630569240,576340150932000,2354075068866300] |