The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 66 |
| 5 | 384 |
| 6 | 3369 |
| 7 | 40365 |
| 8 | 675368 |
| 9 | 14843787 |
| 10 | 412444439 |
| 11 | 14024069358 |
| 12 | 570883006810 |
| 13 | 27368160642418 |
| 14 | 1525274952640101 |
| 15 | 97766102550401217 |
| 16 | 7141331463919539567 |
| 17 | 589726897233157151109 |
| 18 | 54669618693986578729541 |
| 19 | 5653861386413841612952683 |
| 20 | 648651469510725736002532451 |
[1,4,13,66,384,3369,40365,675368,14843787, 412444439,14024069358,570883006810,27368160642418, 1525274952640101,97766102550401217, 7141331463919539567,589726897233157151109, 54669618693986578729541,5653861386413841612952683, 648651469510725736002532451] |