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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 7 |
| 4 | 21 |
| 5 | 46 |
| 6 | 127 |
| 7 | 309 |
| 8 | 832 |
| 9 | 2131 |
| 10 | 5709 |
| 11 | 15010 |
| 12 | 40281 |
| 13 | 107423 |
| 14 | 289314 |
| 15 | 778087 |
| 16 | 2103361 |
| 17 | 5687938 |
| 18 | 15427099 |
| 19 | 41880357 |
| 20 | 113912236 |
| 21 | 310148223 |
| 22 | 845598389 |
| 23 | 2307657222 |
| 24 | 6304306171 |
| 25 | 17237338021 |
| 26 | 47170965082 |
| 27 | 129181447969 |
| 28 | 354027263457 |
| 29 | 970851960736 |
| 30 | 2664008539017 |
[1,1,4,7,21,46,127,309,832,2131,5709,15010,40281, 107423,289314,778087,2103361,5687938,15427099, 41880357,113912236,310148223,845598389,2307657222, 6304306171,17237338021,47170965082,129181447969, 354027263457,970851960736,2664008539017] |