| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 12 |
| 4 | 26 |
| 5 | 50 |
| 6 | 97 |
| 7 | 180 |
| 8 | 332 |
| 9 | 600 |
| 10 | 1076 |
| 11 | 1908 |
| 12 | 3361 |
| 13 | 5878 |
| 14 | 10226 |
| 15 | 17700 |
| 16 | 30510 |
| 17 | 52390 |
| 18 | 89665 |
| 19 | 153000 |
| 20 | 260376 |
| 21 | 442032 |
| 22 | 748776 |
| 23 | 1265832 |
| 24 | 2136001 |
| 25 | 3598250 |
| 26 | 6052062 |
| 27 | 10164540 |
| 28 | 17048642 |
[1,2,6,12,26,50,97,180,332,600,1076,1908,3361, 5878,10226,17700,30510,52390,89665,153000,260376, 442032,748776,1265832,2136001,3598250,6052062, 10164540,17048642] |