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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 20 |
| 4 | 57 |
| 5 | 160 |
| 6 | 454 |
| 7 | 1292 |
| 8 | 3676 |
| 9 | 10452 |
| 10 | 29724 |
| 11 | 84548 |
| 12 | 240480 |
| 13 | 683968 |
| 14 | 1945348 |
| 15 | 5533040 |
| 16 | 15737260 |
| 17 | 44760324 |
| 18 | 127308564 |
| 19 | 362094824 |
| 20 | 1029880752 |
| 21 | 2929216636 |
| 22 | 8331363064 |
| 23 | 23696305892 |
| 24 | 67397723860 |
| 25 | 191694568548 |
| 26 | 545223274608 |
[1,7,20,57,160,454,1292,3676,10452,29724,84548, 240480,683968,1945348,5533040,15737260,44760324, 127308564,362094824,1029880752,2929216636, 8331363064,23696305892,67397723860,191694568548, 545223274608] |