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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 19 |
| 4 | 121 |
| 5 | 1041 |
| 6 | 9931 |
| 7 | 106723 |
| 8 | 1313649 |
| 9 | 17830081 |
| 10 | 265652371 |
| 11 | 4259421651 |
| 12 | 74011854313 |
| 13 | 1374298028689 |
| 14 | 27230459440731 |
| 15 | 573414615381091 |
| 16 | 12723857450638561 |
| 17 | 297915550887491073 |
| 18 | 7328943525355675939 |
| 19 | 188820746254730967571 |
| 20 | 5086439179764958688601 |
[1,1,3,19,121,1041,9931,106723,1313649,17830081, 265652371,4259421651,74011854313,1374298028689, 27230459440731,573414615381091,12723857450638561, 297915550887491073,7328943525355675939, 188820746254730967571,5086439179764958688601] |