The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 225 |
| 3 | 904 |
| 4 | 50849 |
| 5 | 204300 |
| 6 | 11491649 |
| 7 | 46170896 |
| 8 | 2597061825 |
| 9 | 10434418196 |
| 10 | 586924480801 |
| 11 | 2358132341400 |
| 12 | 132642335599201 |
| 13 | 532927474738204 |
| 14 | 29976580920938625 |
| 15 | 120439251158492704 |
| 16 | 6774574645796530049 |
| 17 | 27218737834344612900 |
| 18 | 1531023893369094852449 |
[1,4,225,904,50849,204300,11491649,46170896, 2597061825,10434418196,586924480801,2358132341400, 132642335599201,532927474738204,29976580920938625, 120439251158492704,6774574645796530049, 27218737834344612900,1531023893369094852449] |