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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 13 |
| 4 | 40 |
| 5 | 123 |
| 6 | 403 |
| 7 | 1304 |
| 8 | 4497 |
| 9 | 15299 |
| 10 | 53927 |
| 11 | 187356 |
| 12 | 675747 |
| 13 | 2404640 |
| 14 | 8768830 |
| 15 | 31561721 |
| 16 | 116600798 |
| 17 | 425605898 |
| 18 | 1582744720 |
| 19 | 5818657133 |
| 20 | 21820279075 |
| 21 | 80958949738 |
| 22 | 304934255240 |
| 23 | 1136943454365 |
| 24 | 4307388239096 |
| 25 | 16164654229698 |
| 26 | 61432471877142 |
| 27 | 231365788916348 |
| 28 | 883076005410215 |
| 29 | 3341922934503112 |
[1,2,5,13,40,123,403,1304,4497,15299,53927,187356, 675747,2404640,8768830,31561721,116600798, 425605898,1582744720,5818657133,21820279075, 80958949738,304934255240,1136943454365, 4307388239096,16164654229698,61432471877142, 231365788916348,883076005410215,3341922934503112] |