| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 20 |
| 3 | 75 |
| 4 | 240 |
| 5 | 726 |
| 6 | 2075 |
| 7 | 5620 |
| 8 | 14645 |
| 9 | 36875 |
| 10 | 90057 |
| 11 | 214065 |
| 12 | 497170 |
| 13 | 1129670 |
| 14 | 2517425 |
| 15 | 5512125 |
| 16 | 11871310 |
| 17 | 25184930 |
| 18 | 52686885 |
| 19 | 108786970 |
| 20 | 221894842 |
| 21 | 447455885 |
| 22 | 892609420 |
| 23 | 1762608545 |
| 24 | 3447282925 |
| 25 | 6680871925 |
| 26 | 12835968690 |
| 27 | 24459374345 |
| 28 | 46243132855 |
| 29 | 86773966825 |
| 30 | 161664667295 |
[1,5,20,75,240,726,2075,5620,14645,36875,90057, 214065,497170,1129670,2517425,5512125,11871310, 25184930,52686885,108786970,221894842,447455885, 892609420,1762608545,3447282925,6680871925, 12835968690,24459374345,46243132855,86773966825, 161664667295] |