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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 26 |
| 5 | 68 |
| 6 | 178 |
| 7 | 472 |
| 8 | 1276 |
| 9 | 3462 |
| 10 | 9496 |
| 11 | 26024 |
| 12 | 71956 |
| 13 | 198740 |
| 14 | 552814 |
| 15 | 1535556 |
| 16 | 4290252 |
| 17 | 11968194 |
| 18 | 33553214 |
| 19 | 93917400 |
| 20 | 264020106 |
| 21 | 741024426 |
| 22 | 2087799972 |
| 23 | 5872999754 |
| 24 | 16577458520 |
| 25 | 46720454112 |
| 26 | 132081262316 |
| 27 | 372843051320 |
[1,4,10,26,68,178,472,1276,3462,9496,26024,71956, 198740,552814,1535556,4290252,11968194,33553214, 93917400,264020106,741024426,2087799972, 5872999754,16577458520,46720454112,132081262316, 372843051320] |