The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 25 |
| 5 | 71 |
| 6 | 280 |
| 7 | 925 |
| 8 | 3561 |
| 9 | 12916 |
| 10 | 49346 |
| 11 | 184757 |
| 12 | 710255 |
| 13 | 2704157 |
| 14 | 10427747 |
| 15 | 40119781 |
| 16 | 155288897 |
| 17 | 601080391 |
| 18 | 2334714319 |
| 19 | 9075135301 |
| 20 | 35352181116 |
| 21 | 137846759282 |
| 22 | 538302226628 |
| 23 | 2104098963721 |
| 24 | 8233718962365 |
| 25 | 32247603703576 |
| 26 | 126412458920775 |
| 27 | 495918551104687 |
[1,3,7,25,71,280,925,3561,12916,49346,184757, 710255,2704157,10427747,40119781,155288897, 601080391,2334714319,9075135301,35352181116, 137846759282,538302226628,2104098963721, 8233718962365,32247603703576,126412458920775, 495918551104687] |