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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 74 |
| 5 | 530 |
| 6 | 4550 |
| 7 | 45570 |
| 8 | 521640 |
| 9 | 6717480 |
| 10 | 96117000 |
| 11 | 1512819000 |
| 12 | 25975395600 |
| 13 | 483169486800 |
| 14 | 9678799930800 |
| 15 | 207733600074000 |
| 16 | 4755768505488000 |
| 17 | 115681418156304000 |
| 18 | 2979408725813520000 |
| 19 | 80998627977002736000 |
| 20 | 2317937034142810080000 |
| 21 | 69649003197501567840000 |
| 22 | 2192459412316607834400000 |
| 23 | 72152830779716793506400000 |
| 24 | 2477756318984329979756160000 |
[1,1,3,13,74,530,4550,45570,521640,6717480, 96117000,1512819000,25975395600,483169486800, 9678799930800,207733600074000,4755768505488000, 115681418156304000,2979408725813520000, 80998627977002736000,2317937034142810080000, 69649003197501567840000,2192459412316607834400000, 72152830779716793506400000, 2477756318984329979756160000] |