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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 28 |
| 4 | 120 |
| 5 | 526 |
| 6 | 2381 |
| 7 | 10922 |
| 8 | 50757 |
| 9 | 238129 |
| 10 | 1125448 |
| 11 | 5350048 |
| 12 | 25556511 |
| 13 | 122562645 |
| 14 | 589753134 |
| 15 | 2845909120 |
| 16 | 13766991676 |
| 17 | 66739791983 |
| 18 | 324149453400 |
| 19 | 1576978364648 |
| 20 | 7683288284434 |
| 21 | 37483722315418 |
| 22 | 183086192515193 |
| 23 | 895234712523878 |
| 24 | 4381718084447971 |
| 25 | 21465519743894719 |
| 26 | 105243595782959115 |
[1,2,7,28,120,526,2381,10922,50757,238129,1125448, 5350048,25556511,122562645,589753134,2845909120, 13766991676,66739791983,324149453400, 1576978364648,7683288284434,37483722315418, 183086192515193,895234712523878,4381718084447971, 21465519743894719,105243595782959115] |