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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 28 |
| 5 | 80 |
| 6 | 343 |
| 7 | 1109 |
| 8 | 4957 |
| 9 | 17265 |
| 10 | 79054 |
| 11 | 289714 |
| 12 | 1348498 |
| 13 | 5126901 |
| 14 | 24142264 |
| 15 | 94383071 |
| 16 | 448304541 |
| 17 | 1791386504 |
| 18 | 8565590298 |
| 19 | 34836181497 |
| 20 | 167448617851 |
| 21 | 690969359292 |
| 22 | 3335440944368 |
| 23 | 13931963736742 |
| 24 | 67487310816370 |
| 25 | 284820772882426 |
| 26 | 1383712783056099 |
| 27 | 5891971199940838 |
| 28 | 28694836974139199 |
[1,1,3,7,28,80,343,1109,4957,17265,79054,289714, 1348498,5126901,24142264,94383071,448304541, 1791386504,8565590298,34836181497,167448617851, 690969359292,3335440944368,13931963736742, 67487310816370,284820772882426,1383712783056099, 5891971199940838,28694836974139199] |