The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 9 |
| 2 | 25 |
| 3 | 57 |
| 4 | 149 |
| 5 | 389 |
| 6 | 1045 |
| 7 | 2837 |
| 8 | 7789 |
| 9 | 21549 |
| 10 | 60005 |
| 11 | 167957 |
| 12 | 472169 |
| 13 | 1332249 |
| 14 | 3770785 |
| 15 | 10701617 |
| 16 | 30442909 |
| 17 | 86779229 |
| 18 | 247817845 |
| 19 | 708837797 |
| 20 | 2030401509 |
| 21 | 5823331109 |
| 22 | 16720830525 |
| 23 | 48060737357 |
| 24 | 138268935049 |
| 25 | 398126270889 |
[1,9,25,57,149,389,1045,2837,7789,21549,60005, 167957,472169,1332249,3770785,10701617,30442909, 86779229,247817845,708837797,2030401509, 5823331109,16720830525,48060737357,138268935049, 398126270889] |