| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 21 |
| 4 | 92 |
| 5 | 291 |
| 6 | 981 |
| 7 | 2871 |
| 8 | 8134 |
| 9 | 21131 |
| 10 | 52481 |
| 11 | 122759 |
| 12 | 275356 |
| 13 | 590289 |
| 14 | 1220811 |
| 15 | 2436045 |
| 16 | 4715827 |
| 17 | 8866230 |
| 18 | 16246890 |
| 19 | 29054190 |
| 20 | 50830264 |
| 21 | 87104226 |
| 22 | 146467614 |
| 23 | 241934106 |
| 24 | 393098860 |
| 25 | 628867434 |
| 26 | 991602894 |
| 27 | 1542350194 |
| 28 | 2368492984 |
| 29 | 3593354974 |
[1,1,7,21,92,291,981,2871,8134,21131,52481,122759, 275356,590289,1220811,2436045,4715827,8866230, 16246890,29054190,50830264,87104226,146467614, 241934106,393098860,628867434,991602894, 1542350194,2368492984,3593354974] |