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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 28 |
| 5 | 90 |
| 6 | 306 |
| 7 | 1078 |
| 8 | 3984 |
| 9 | 15228 |
| 10 | 60580 |
| 11 | 248556 |
| 12 | 1055088 |
| 13 | 4606264 |
| 14 | 20712888 |
| 15 | 95550120 |
| 16 | 452450176 |
| 17 | 2193051408 |
| 18 | 10882018224 |
| 19 | 55166645008 |
| 20 | 285683655360 |
| 21 | 1508969248416 |
| 22 | 8127210649888 |
| 23 | 44582377997664 |
| 24 | 249000413522688 |
| 25 | 1414657929227200 |
| 26 | 8172653475494976 |
[1,3,9,28,90,306,1078,3984,15228,60580,248556, 1055088,4606264,20712888,95550120,452450176, 2193051408,10882018224,55166645008,285683655360, 1508969248416,8127210649888,44582377997664, 249000413522688,1414657929227200,8172653475494976] |