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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 36 |
| 4 | 640 |
| 5 | 21888 |
| 6 | 1451008 |
| 7 | 188941312 |
| 8 | 48768745472 |
| 9 | 25069815595008 |
| 10 | 25722272102744064 |
| 11 | 52730972085034156032 |
| 12 | 216091838647321476726784 |
| 13 | 1770657164881170759078117376 |
| 14 | 29013990909330956353981535748096 |
[1,1,4,36,640,21888,1451008,188941312,48768745472, 25069815595008,25722272102744064, 52730972085034156032,216091838647321476726784, 1770657164881170759078117376, 29013990909330956353981535748096] |