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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 25 |
| 3 | 75 |
| 4 | 220 |
| 5 | 731 |
| 6 | 2419 |
| 7 | 7900 |
| 8 | 25645 |
| 9 | 83685 |
| 10 | 273504 |
| 11 | 893195 |
| 12 | 2915411 |
| 13 | 9518108 |
| 14 | 31079021 |
| 15 | 101478805 |
| 16 | 331335348 |
| 17 | 1081839931 |
| 18 | 3532345439 |
| 19 | 11533574036 |
| 20 | 37658571753 |
| 21 | 122959986781 |
| 22 | 401480186136 |
| 23 | 1310884882811 |
| 24 | 4280209057195 |
[4,25,75,220,731,2419,7900,25645,83685,273504, 893195,2915411,9518108,31079021,101478805, 331335348,1081839931,3532345439,11533574036, 37658571753,122959986781,401480186136, 1310884882811,4280209057195] |