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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 4 |
| 6 | 9 |
| 7 | 21 |
| 8 | 51 |
| 9 | 127 |
| 10 | 323 |
| 11 | 835 |
| 12 | 2188 |
| 13 | 5798 |
| 14 | 15511 |
| 15 | 41835 |
| 16 | 113634 |
| 17 | 310572 |
| 18 | 853467 |
| 19 | 2356779 |
| 20 | 6536382 |
| 21 | 18199284 |
| 22 | 50852019 |
| 23 | 142547559 |
| 24 | 400763223 |
| 25 | 1129760415 |
| 26 | 3192727797 |
| 27 | 9043402501 |
| 28 | 25669818476 |
| 29 | 73007772802 |
| 30 | 208023278209 |
[1,0,1,1,2,4,9,21,51,127,323,835,2188,5798,15511, 41835,113634,310572,853467,2356779,6536382, 18199284,50852019,142547559,400763223,1129760415, 3192727797,9043402501,25669818476,73007772802, 208023278209] |