The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 14 |
| 3 | 60 |
| 4 | 248 |
| 5 | 336 |
| 6 | 4064 |
| 7 | 15120 |
| 8 | 16380 |
| 9 | 261888 |
| 10 | 1089270 |
| 11 | 11784960 |
| 12 | 16775168 |
| 13 | 22766400 |
| 14 | 71495424 |
| 15 | 229909120 |
| 16 | 689727360 |
| 17 | 738152448 |
| 18 | 4294934528 |
| 19 | 7091219520 |
| 20 | 15999197760 |
| 21 | 21930739200 |
| 22 | 25500590080 |
| 23 | 33216860160 |
[3,14,60,248,336,4064,15120,16380,261888,1089270, 11784960,16775168,22766400,71495424,229909120, 689727360,738152448,4294934528,7091219520, 15999197760,21930739200,25500590080,33216860160] |