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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 35 |
| 5 | 116 |
| 6 | 500 |
| 7 | 1860 |
| 8 | 8288 |
| 9 | 33222 |
| 10 | 151006 |
| 11 | 634144 |
| 12 | 2927959 |
| 13 | 12686672 |
| 14 | 59289782 |
| 15 | 262829326 |
| 16 | 1239619599 |
| 17 | 5592148566 |
| 18 | 26562347627 |
| 19 | 121489768762 |
| 20 | 580326142766 |
| 21 | 2683779258274 |
| 22 | 12878825133211 |
| 23 | 60098900650217 |
| 24 | 289507169955153 |
| 25 | 1361099053157427 |
| 26 | 6577911281816518 |
| 27 | 31119637635957412 |
[1,1,3,9,35,116,500,1860,8288,33222,151006,634144, 2927959,12686672,59289782,262829326,1239619599, 5592148566,26562347627,121489768762,580326142766, 2683779258274,12878825133211,60098900650217, 289507169955153,1361099053157427,6577911281816518, 31119637635957412] |