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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 8 |
| 5 | 18 |
| 6 | 52 |
| 7 | 116 |
| 8 | 296 |
| 9 | 650 |
| 10 | 1556 |
| 11 | 3372 |
| 12 | 7768 |
| 13 | 16660 |
| 14 | 37416 |
| 15 | 79592 |
| 16 | 175568 |
| 17 | 371034 |
| 18 | 807604 |
| 19 | 1697660 |
| 20 | 3657464 |
| 21 | 7654460 |
| 22 | 16357496 |
| 23 | 34106712 |
| 24 | 72407728 |
| 25 | 150499908 |
| 26 | 317777032 |
| 27 | 658707896 |
| 28 | 1384524656 |
| 29 | 2863150440 |
| 30 | 5994736336 |
[0,1,2,8,18,52,116,296,650,1556,3372,7768,16660, 37416,79592,175568,371034,807604,1697660,3657464, 7654460,16357496,34106712,72407728,150499908, 317777032,658707896,1384524656,2863150440, 5994736336] |