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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 13 |
| 6 | 40 |
| 7 | 100 |
| 8 | 291 |
| 9 | 797 |
| 10 | 2273 |
| 11 | 6389 |
| 12 | 18264 |
| 13 | 51916 |
| 14 | 148666 |
| 15 | 425529 |
| 16 | 1221900 |
| 17 | 3511507 |
| 18 | 10111043 |
| 19 | 29142941 |
| 20 | 84112009 |
| 21 | 243000149 |
| 22 | 702758065 |
| 23 | 2034150215 |
| 24 | 5892907566 |
| 25 | 17084615940 |
| 26 | 49567063847 |
| 27 | 143902155133 |
| 28 | 418032946298 |
| 29 | 1215076634226 |
| 30 | 3533715961160 |
| 31 | 10282042126394 |
| 32 | 29931877173282 |
| 33 | 87173224346464 |
| 34 | 253989569994664 |
[1,0,1,2,6,13,40,100,291,797,2273,6389,18264, 51916,148666,425529,1221900,3511507,10111043, 29142941,84112009,243000149,702758065,2034150215, 5892907566,17084615940,49567063847,143902155133, 418032946298,1215076634226,3533715961160, 10282042126394,29931877173282,87173224346464, 253989569994664] |