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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 19 |
| 3 | 86 |
| 4 | 1060 |
| 5 | 13276 |
| 6 | 215308 |
| 7 | 3086544 |
| 8 | 68937280 |
| 9 | 1552257216 |
| 10 | 40750688448 |
| 11 | 987692033664 |
| 12 | 31883024335104 |
| 13 | 1036810188322560 |
| 14 | 37597332892066560 |
| 15 | 1285416947916933120 |
| 16 | 54309158991453634560 |
| 17 | 2309262618253981040640 |
| 18 | 106842526312699253145600 |
[1,3,19,86,1060,13276,215308,3086544,68937280, 1552257216,40750688448,987692033664, 31883024335104,1036810188322560,37597332892066560, 1285416947916933120,54309158991453634560, 2309262618253981040640,106842526312699253145600] |