| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 19 |
| 4 | 65 |
| 5 | 241 |
| 6 | 905 |
| 7 | 3599 |
| 8 | 14425 |
| 9 | 59534 |
| 10 | 249329 |
| 11 | 1056921 |
| 12 | 4552398 |
| 13 | 19735824 |
| 14 | 86589754 |
| 15 | 382354053 |
| 16 | 1700890992 |
| 17 | 7617683252 |
| 18 | 34282253718 |
| 19 | 155195308290 |
| 20 | 705421980080 |
| 21 | 3220837523649 |
| 22 | 14762428021071 |
| 23 | 67892389467223 |
| 24 | 313323316552737 |
| 25 | 1450092203641912 |
| 26 | 6730788726949523 |
| 27 | 31321971802780059 |
[1,2,6,19,65,241,905,3599,14425,59534,249329, 1056921,4552398,19735824,86589754,382354053, 1700890992,7617683252,34282253718,155195308290, 705421980080,3220837523649,14762428021071, 67892389467223,313323316552737,1450092203641912, 6730788726949523,31321971802780059] |