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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 9 |
| 5 | 20 |
| 6 | 46 |
| 7 | 106 |
| 8 | 248 |
| 9 | 584 |
| 10 | 1389 |
| 11 | 3329 |
| 12 | 8047 |
| 13 | 19607 |
| 14 | 48167 |
| 15 | 119287 |
| 16 | 297829 |
| 17 | 749632 |
| 18 | 1902044 |
| 19 | 4864553 |
| 20 | 12538933 |
| 21 | 32568528 |
| 22 | 85224251 |
| 23 | 224618900 |
| 24 | 596106393 |
| 25 | 1592429464 |
| 26 | 4280667705 |
| 27 | 11575188106 |
| 28 | 31474407317 |
| 29 | 86029586086 |
| 30 | 236292044931 |
| 31 | 651952466845 |
[1,1,2,4,9,20,46,106,248,584,1389,3329,8047,19607, 48167,119287,297829,749632,1902044,4864553, 12538933,32568528,85224251,224618900,596106393, 1592429464,4280667705,11575188106,31474407317, 86029586086,236292044931,651952466845] |