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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 26 |
| 4 | 76 |
| 5 | 216 |
| 6 | 590 |
| 7 | 1554 |
| 8 | 3988 |
| 9 | 9988 |
| 10 | 24464 |
| 11 | 58794 |
| 12 | 138866 |
| 13 | 322808 |
| 14 | 739658 |
| 15 | 1672372 |
| 16 | 3734848 |
| 17 | 8245956 |
| 18 | 18012114 |
| 19 | 38952586 |
| 20 | 83448832 |
| 21 | 177194716 |
| 22 | 373111970 |
| 23 | 779430870 |
| 24 | 1615995262 |
| 25 | 3326484686 |
| 26 | 6800794428 |
| 27 | 13813260736 |
| 28 | 27881653590 |
| 29 | 55942340000 |
| 30 | 111601021856 |
[1,2,8,26,76,216,590,1554,3988,9988,24464,58794, 138866,322808,739658,1672372,3734848,8245956, 18012114,38952586,83448832,177194716,373111970, 779430870,1615995262,3326484686,6800794428, 13813260736,27881653590,55942340000,111601021856] |