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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 21 |
| 3 | 76 |
| 4 | 218 |
| 5 | 568 |
| 6 | 1295 |
| 7 | 2688 |
| 8 | 5108 |
| 9 | 9084 |
| 10 | 15457 |
| 11 | 25188 |
| 12 | 39646 |
| 13 | 60512 |
| 14 | 89635 |
| 15 | 129224 |
| 16 | 182088 |
| 17 | 251708 |
| 18 | 341805 |
| 19 | 456868 |
| 20 | 601938 |
| 21 | 782344 |
| 22 | 1004327 |
| 23 | 1274776 |
| 24 | 1601612 |
| 25 | 1994244 |
| 26 | 2462873 |
| 27 | 3018108 |
| 28 | 3671398 |
| 29 | 4434624 |
| 30 | 5320555 |
| 31 | 6345320 |
[4,21,76,218,568,1295,2688,5108,9084,15457,25188, 39646,60512,89635,129224,182088,251708,341805, 456868,601938,782344,1004327,1274776,1601612, 1994244,2462873,3018108,3671398,4434624,5320555, 6345320] |