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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 58 |
| 5 | 236 |
| 6 | 1061 |
| 7 | 4706 |
| 8 | 21650 |
| 9 | 99606 |
| 10 | 466518 |
| 11 | 2190098 |
| 12 | 10383439 |
| 13 | 49367094 |
| 14 | 236113304 |
| 15 | 1132153966 |
| 16 | 5450278252 |
| 17 | 26293717423 |
| 18 | 127207867136 |
| 19 | 616512989395 |
| 20 | 2994208483998 |
| 21 | 14563343462396 |
| 22 | 70948537314877 |
| 23 | 346067519427222 |
| 24 | 1690198831088196 |
| 25 | 8263542216340939 |
| 26 | 40443671167837558 |
| 27 | 198115841544627367 |
[1,1,4,13,58,236,1061,4706,21650,99606,466518, 2190098,10383439,49367094,236113304,1132153966, 5450278252,26293717423,127207867136,616512989395, 2994208483998,14563343462396,70948537314877, 346067519427222,1690198831088196,8263542216340939, 40443671167837558,198115841544627367] |