The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 205 |
| 4 | 505 |
| 5 | 20705 |
| 6 | 40505 |
| 7 | 168305 |
| 8 | 408545 |
| 9 | 1342505 |
| 10 | 1660705 |
| 11 | 2084645 |
| 12 | 4091005 |
| 13 | 10201505 |
| 14 | 16322105 |
| 15 | 16750345 |
| 16 | 16998805 |
| 17 | 37217545 |
| 18 | 49985405 |
| 19 | 55042705 |
| 20 | 117165905 |
| 21 | 135593005 |
| 22 | 167731205 |
| 23 | 186678805 |
| 24 | 210549145 |
| 25 | 218301905 |
| 26 | 418261705 |
[1,5,205,505,20705,40505,168305,408545,1342505, 1660705,2084645,4091005,10201505,16322105, 16750345,16998805,37217545,49985405,55042705, 117165905,135593005,167731205,186678805,210549145, 218301905,418261705] |