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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 64 |
| 3 | 1296 |
| 4 | 29888 |
| 5 | 745856 |
| 6 | 19614464 |
| 7 | 535394560 |
| 8 | 15026146304 |
| 9 | 430901082112 |
| 10 | 12570964738048 |
| 11 | 371918487789568 |
| 12 | 11132402289049600 |
| 13 | 336515403043962880 |
| 14 | 10258388252467200000 |
| 15 | 315006202191320514560 |
| 16 | 9734768426532836474880 |
| 17 | 302531413305855206490112 |
| 18 | 9448885107650550229368832 |
[4,64,1296,29888,745856,19614464,535394560, 15026146304,430901082112,12570964738048, 371918487789568,11132402289049600, 336515403043962880,10258388252467200000, 315006202191320514560,9734768426532836474880, 302531413305855206490112, 9448885107650550229368832] |