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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 13 |
| 2 | 42 |
| 3 | 136 |
| 4 | 440 |
| 5 | 1424 |
| 6 | 4609 |
| 7 | 14918 |
| 8 | 48285 |
| 9 | 156284 |
| 10 | 505844 |
| 11 | 1637264 |
| 12 | 5299328 |
| 13 | 17152321 |
| 14 | 55516872 |
| 15 | 179691313 |
| 16 | 581606398 |
| 17 | 1882483892 |
| 18 | 6093030640 |
| 19 | 19721296176 |
| 20 | 63831867233 |
| 21 | 206604436042 |
| 22 | 668716032329 |
| 23 | 2164431415224 |
| 24 | 7005609443656 |
| 25 | 22675037578848 |
| 26 | 73392234228496 |
| 27 | 237548450639617 |
| 28 | 768872442629260 |
[4,13,42,136,440,1424,4609,14918,48285,156284, 505844,1637264,5299328,17152321,55516872, 179691313,581606398,1882483892,6093030640, 19721296176,63831867233,206604436042,668716032329, 2164431415224,7005609443656,22675037578848, 73392234228496,237548450639617,768872442629260] |