The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 3 |
| 1 | 28 |
| 2 | 145 |
| 3 | 550 |
| 4 | 1705 |
| 5 | 4576 |
| 6 | 11011 |
| 7 | 24310 |
| 8 | 50050 |
| 9 | 97240 |
| 10 | 179894 |
| 11 | 319124 |
| 12 | 545870 |
| 13 | 904400 |
| 14 | 1456730 |
| 15 | 2288132 |
| 16 | 3513917 |
| 17 | 5287700 |
| 18 | 7811375 |
| 19 | 11347050 |
| 20 | 16231215 |
| 21 | 22891440 |
| 22 | 31865925 |
| 23 | 43826250 |
| 24 | 59603700 |
| 25 | 80219568 |
| 26 | 106919868 |
| 27 | 141214920 |
[3,28,145,550,1705,4576,11011,24310,50050,97240, 179894,319124,545870,904400,1456730,2288132, 3513917,5287700,7811375,11347050,16231215, 22891440,31865925,43826250,59603700,80219568, 106919868,141214920] |