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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 4 |
| 6 | 13 |
| 7 | 28 |
| 8 | 49 |
| 9 | 76 |
| 10 | 487 |
| 11 | 3766 |
| 12 | 20956 |
| 13 | 91261 |
| 14 | 385483 |
| 15 | 3099937 |
| 16 | 40032793 |
| 17 | 511624885 |
| 18 | 5661397930 |
| 19 | 61479664849 |
| 20 | 927273309259 |
| 21 | 20003424034360 |
| 22 | 509150633289499 |
| 23 | 13132668672579046 |
| 24 | 346049894030528596 |
[1,4,13,28,49,76,487,3766,20956,91261,385483, 3099937,40032793,511624885,5661397930,61479664849, 927273309259,20003424034360,509150633289499, 13132668672579046,346049894030528596] |