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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 23 |
| 4 | 175 |
| 5 | 1662 |
| 6 | 18937 |
| 7 | 251729 |
| 8 | 3824282 |
| 9 | 65361237 |
| 10 | 1241218963 |
| 11 | 25928015368 |
| 12 | 590852003947 |
| 13 | 14586471744301 |
| 14 | 387798817072596 |
| 15 | 11046531316503163 |
| 16 | 335640299372252595 |
| 17 | 10835556229612637150 |
| 18 | 370383732831919278037 |
| 19 | 13363914680277923634517 |
[1,1,4,23,175,1662,18937,251729,3824282,65361237, 1241218963,25928015368,590852003947, 14586471744301,387798817072596,11046531316503163, 335640299372252595,10835556229612637150, 370383732831919278037,13363914680277923634517] |