The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 23 |
| 4 | 89 |
| 5 | 325 |
| 6 | 1123 |
| 7 | 3750 |
| 8 | 12174 |
| 9 | 38682 |
| 10 | 120750 |
| 11 | 371478 |
| 12 | 1128810 |
| 13 | 3394159 |
| 14 | 10112987 |
| 15 | 29892425 |
| 16 | 87737471 |
| 17 | 255912115 |
| 18 | 742272853 |
| 19 | 2142128604 |
| 20 | 6153811500 |
| 21 | 17605105380 |
| 22 | 50174676300 |
| 23 | 142501128540 |
| 24 | 403422149220 |
| 25 | 1138714934125 |
| 26 | 3205372562369 |
| 27 | 8999834877995 |
| 28 | 25209180070037 |
[1,5,23,89,325,1123,3750,12174,38682,120750, 371478,1128810,3394159,10112987,29892425,87737471, 255912115,742272853,2142128604,6153811500, 17605105380,50174676300,142501128540,403422149220, 1138714934125,3205372562369,8999834877995, 25209180070037] |