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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 4 |
| 3 | 25 |
| 4 | 160 |
| 5 | 1193 |
| 6 | 9585 |
| 7 | 80020 |
| 8 | 686048 |
| 9 | 6003530 |
| 10 | 53378283 |
| 11 | 480532488 |
| 12 | 4369582734 |
| 13 | 40063566855 |
| 14 | 369893939287 |
| 15 | 3435376839800 |
| 16 | 32069022099022 |
| 17 | 300694113015105 |
| 18 | 2830466318006780 |
| 19 | 26735673312004455 |
| 20 | 253315661161665338 |
| 21 | 2406763761677705769 |
| 22 | 22923886160712831134 |
| 23 | 218839439542390117580 |
[0,4,25,160,1193,9585,80020,686048,6003530, 53378283,480532488,4369582734,40063566855, 369893939287,3435376839800,32069022099022, 300694113015105,2830466318006780, 26735673312004455,253315661161665338, 2406763761677705769,22923886160712831134, 218839439542390117580] |