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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 27 |
| 3 | 110 |
| 4 | 429 |
| 5 | 1638 |
| 6 | 6187 |
| 7 | 23238 |
| 8 | 87021 |
| 9 | 325358 |
| 10 | 1215435 |
| 11 | 4538430 |
| 12 | 16942381 |
| 13 | 63239286 |
| 14 | 236031147 |
| 15 | 880918070 |
| 16 | 3287706669 |
| 17 | 12270039678 |
| 18 | 45792714187 |
| 19 | 170901341358 |
| 20 | 637813699821 |
| 21 | 2380355555078 |
| 22 | 8883612714795 |
| 23 | 33154103692710 |
| 24 | 123732818833261 |
| 25 | 461777205194766 |
| 26 | 1723376069054667 |
[1,6,27,110,429,1638,6187,23238,87021,325358, 1215435,4538430,16942381,63239286,236031147, 880918070,3287706669,12270039678,45792714187, 170901341358,637813699821,2380355555078, 8883612714795,33154103692710,123732818833261, 461777205194766,1723376069054667] |