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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 62 |
| 5 | 370 |
| 6 | 2397 |
| 7 | 16345 |
| 8 | 115376 |
| 9 | 834786 |
| 10 | 6152285 |
| 11 | 45990120 |
| 12 | 347673108 |
| 13 | 2652283517 |
| 14 | 20385035972 |
| 15 | 157656007680 |
| 16 | 1225743120520 |
| 17 | 9572972899946 |
| 18 | 75056029550721 |
| 19 | 590469939950716 |
| 20 | 4659115833115680 |
| 21 | 36859770507695688 |
[1,3,12,62,370,2397,16345,115376,834786,6152285, 45990120,347673108,2652283517,20385035972, 157656007680,1225743120520,9572972899946, 75056029550721,590469939950716,4659115833115680, 36859770507695688] |