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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 36 |
| 6 | 214 |
| 7 | 1157 |
| 8 | 6312 |
| 9 | 33048 |
| 10 | 167928 |
| 11 | 883872 |
| 12 | 4881168 |
| 13 | 27546779 |
| 14 | 155696585 |
| 15 | 877515379 |
| 16 | 4936018176 |
| 17 | 27770211072 |
| 18 | 156728297088 |
| 19 | 889046473445 |
| 20 | 5067822213734 |
| 21 | 28988793435209 |
| 22 | 166189019079168 |
| 23 | 954240788994048 |
| 24 | 5486915505475584 |
| 25 | 31597040041716690 |
[1,1,1,4,36,214,1157,6312,33048,167928,883872, 4881168,27546779,155696585,877515379,4936018176, 27770211072,156728297088,889046473445, 5067822213734,28988793435209,166189019079168, 954240788994048,5486915505475584, 31597040041716690] |