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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 5 |
| 7 | 12 |
| 8 | 28 |
| 9 | 68 |
| 10 | 181 |
| 11 | 531 |
| 12 | 1671 |
| 13 | 5491 |
| 14 | 18627 |
| 15 | 65299 |
| 16 | 237880 |
| 17 | 903907 |
| 18 | 3580619 |
| 19 | 14729777 |
| 20 | 62639952 |
| 21 | 274442521 |
| 22 | 1236730244 |
| 23 | 5729809348 |
| 24 | 27292248240 |
| 25 | 133614280479 |
| 26 | 671803041553 |
| 27 | 3464970976743 |
| 28 | 18309428363425 |
| 29 | 99010800275743 |
| 30 | 547462187824465 |
| 31 | 3093329527120022 |
[1,0,1,1,1,2,5,12,28,68,181,531,1671,5491,18627, 65299,237880,903907,3580619,14729777,62639952, 274442521,1236730244,5729809348,27292248240, 133614280479,671803041553,3464970976743, 18309428363425,99010800275743,547462187824465, 3093329527120022] |