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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 9 |
| 3 | 103 |
| 4 | 421 |
| 5 | 4734 |
| 6 | 9889 |
| 7 | 44290 |
| 8 | 2578709 |
| 9 | 10359126 |
| 10 | 23296961 |
| 11 | 266625697 |
| 12 | 1089799749 |
| 13 | 12254422936 |
| 14 | 25598645621 |
| 15 | 114649005420 |
| 16 | 6675240959981 |
| 17 | 26815612845344 |
| 18 | 60306466650669 |
| 19 | 690186746002703 |
| 20 | 2821053450661481 |
| 21 | 31721774703278994 |
| 22 | 66264602857219469 |
[1,4,9,103,421,4734,9889,44290,2578709,10359126, 23296961,266625697,1089799749,12254422936, 25598645621,114649005420,6675240959981, 26815612845344,60306466650669,690186746002703, 2821053450661481,31721774703278994, 66264602857219469] |