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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 44 |
| 5 | 146 |
| 6 | 642 |
| 7 | 2239 |
| 8 | 10080 |
| 9 | 37666 |
| 10 | 171218 |
| 11 | 663592 |
| 12 | 3053331 |
| 13 | 12116439 |
| 14 | 56196754 |
| 15 | 227206025 |
| 16 | 1059367428 |
| 17 | 4350268844 |
| 18 | 20366889356 |
| 19 | 84658346439 |
| 20 | 397770494430 |
| 21 | 1669447188227 |
| 22 | 7866672042155 |
| 23 | 33291883541903 |
| 24 | 157236375815510 |
| 25 | 670231722511354 |
| 26 | 3171728208270064 |
| 27 | 13602768720471067 |
[1,1,4,11,44,146,642,2239,10080,37666,171218, 663592,3053331,12116439,56196754,227206025, 1059367428,4350268844,20366889356,84658346439, 397770494430,1669447188227,7866672042155, 33291883541903,157236375815510,670231722511354, 3171728208270064,13602768720471067] |