The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 10 |
| 2 | 50 |
| 3 | 210 |
| 4 | 850 |
| 5 | 3410 |
| 6 | 13650 |
| 7 | 54610 |
| 8 | 218450 |
| 9 | 873810 |
| 10 | 3495250 |
| 11 | 13981010 |
| 12 | 55924050 |
| 13 | 223696210 |
| 14 | 894784850 |
| 15 | 3579139410 |
| 16 | 14316557650 |
| 17 | 57266230610 |
| 18 | 229064922450 |
| 19 | 916259689810 |
| 20 | 3665038759250 |
| 21 | 14660155037010 |
| 22 | 58640620148050 |
[1,10,50,210,850,3410,13650,54610,218450,873810, 3495250,13981010,55924050,223696210,894784850, 3579139410,14316557650,57266230610,229064922450, 916259689810,3665038759250,14660155037010, 58640620148050] |