The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 13 |
| 4 | 39 |
| 5 | 126 |
| 6 | 425 |
| 7 | 1450 |
| 8 | 5047 |
| 9 | 17992 |
| 10 | 65529 |
| 11 | 241627 |
| 12 | 898491 |
| 13 | 3371044 |
| 14 | 12776049 |
| 15 | 48846741 |
| 16 | 187977471 |
| 17 | 727253048 |
| 18 | 2828708897 |
| 19 | 11061969253 |
| 20 | 43468440939 |
| 21 | 171505019064 |
| 22 | 679127110969 |
| 23 | 2698669685594 |
| 24 | 10760234246547 |
| 25 | 43037175215226 |
| 26 | 172614370182825 |
| 27 | 694115046618895 |
| 28 | 2798076426790047 |
[1,2,5,13,39,126,425,1450,5047,17992,65529,241627, 898491,3371044,12776049,48846741,187977471, 727253048,2828708897,11061969253,43468440939, 171505019064,679127110969,2698669685594, 10760234246547,43037175215226,172614370182825, 694115046618895,2798076426790047] |