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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 16 |
| 4 | 42 |
| 5 | 106 |
| 6 | 268 |
| 7 | 650 |
| 8 | 1580 |
| 9 | 3750 |
| 10 | 8862 |
| 11 | 20598 |
| 12 | 47776 |
| 13 | 109248 |
| 14 | 248966 |
| 15 | 562630 |
| 16 | 1264780 |
| 17 | 2823958 |
| 18 | 6282198 |
| 19 | 13884820 |
| 20 | 30590124 |
| 21 | 67051982 |
| 22 | 146463790 |
| 23 | 318588916 |
| 24 | 690882926 |
| 25 | 1492592450 |
| 26 | 3215372064 |
| 27 | 6904561416 |
| 28 | 14786529836 |
| 29 | 31574656096 |
| 30 | 67261524262 |
[1,2,6,16,42,106,268,650,1580,3750,8862,20598, 47776,109248,248966,562630,1264780,2823958, 6282198,13884820,30590124,67051982,146463790, 318588916,690882926,1492592450,3215372064, 6904561416,14786529836,31574656096,67261524262] |