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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 8 |
| 3 | 19 |
| 4 | 38 |
| 5 | 114 |
| 6 | 251 |
| 7 | 612 |
| 8 | 1656 |
| 9 | 3758 |
| 10 | 9630 |
| 11 | 24258 |
| 12 | 57548 |
| 13 | 146898 |
| 14 | 360946 |
| 15 | 880960 |
| 16 | 2217967 |
| 17 | 5429271 |
| 18 | 13419200 |
| 19 | 33424298 |
| 20 | 82079277 |
| 21 | 203571196 |
| 22 | 504206276 |
| 23 | 1242741927 |
| 24 | 3081338174 |
| 25 | 7616293969 |
| 26 | 18815746878 |
| 27 | 46600839533 |
| 28 | 115150972966 |
[2,8,19,38,114,251,612,1656,3758,9630,24258,57548, 146898,360946,880960,2217967,5429271,13419200, 33424298,82079277,203571196,504206276,1242741927, 3081338174,7616293969,18815746878,46600839533, 115150972966] |