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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 37 |
| 3 | 415 |
| 4 | 3745 |
| 5 | 31471 |
| 6 | 257257 |
| 7 | 2078455 |
| 8 | 16704865 |
| 9 | 133935391 |
| 10 | 1072633177 |
| 11 | 8585561095 |
| 12 | 68702163985 |
| 13 | 549687102511 |
| 14 | 4397773276297 |
| 15 | 35183283965335 |
| 16 | 281470638631105 |
| 17 | 2251782504544831 |
| 18 | 18014329402322617 |
| 19 | 144114912035163175 |
| 20 | 1152920401607386225 |
[0,1,37,415,3745,31471,257257,2078455,16704865, 133935391,1072633177,8585561095,68702163985, 549687102511,4397773276297,35183283965335, 281470638631105,2251782504544831, 18014329402322617,144114912035163175, 1152920401607386225] |