The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 20 |
| 2 | 306 |
| 3 | 7376 |
| 4 | 273956 |
| 5 | 15345156 |
| 6 | 1274990124 |
| 7 | 155024945978 |
| 8 | 27422185371264 |
| 9 | 6981850496603886 |
| 10 | 2547185424690611836 |
[2,20,306,7376,273956,15345156,1274990124, 155024945978,27422185371264,6981850496603886, 2547185424690611836] |