The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 90 |
| 4 | 1552 |
| 5 | 9902 |
| 6 | 41152 |
| 7 | 133181 |
| 8 | 364793 |
| 9 | 885880 |
| 10 | 1963116 |
| 11 | 4046800 |
| 12 | 7865858 |
| 13 | 14559622 |
| 14 | 25856844 |
| 15 | 44314491 |
| 16 | 73631219 |
| 17 | 119053056 |
| 18 | 187891752 |
| 19 | 290179494 |
[0,0,90,1552,9902,41152,133181,364793,885880, 1963116,4046800,7865858,14559622,25856844, 44314491,73631219,119053056,187891752,290179494] |