The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 18 |
| 3 | 250 |
| 4 | 4114 |
| 5 | 74274 |
| 6 | 1422370 |
| 7 | 28375578 |
| 8 | 583343970 |
| 9 | 12271614850 |
| 10 | 262896435954 |
| 11 | 5715805729274 |
| 12 | 125797580340978 |
| 13 | 2797216275743010 |
| 14 | 62745424152317314 |
| 15 | 1418139209556260250 |
| 16 | 32263795396317233090 |
| 17 | 738290052194219833346 |
| 18 | 16981168956515987563730 |
[1,2,18,250,4114,74274,1422370,28375578,583343970, 12271614850,262896435954,5715805729274, 125797580340978,2797216275743010, 62745424152317314,1418139209556260250, 32263795396317233090,738290052194219833346, 16981168956515987563730] |