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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 46 |
| 5 | 149 |
| 6 | 690 |
| 7 | 2497 |
| 8 | 11744 |
| 9 | 45062 |
| 10 | 214536 |
| 11 | 853892 |
| 12 | 4098631 |
| 13 | 16729527 |
| 14 | 80801096 |
| 15 | 335978483 |
| 16 | 1630298162 |
| 17 | 6876922865 |
| 18 | 33488217825 |
| 19 | 142893840268 |
| 20 | 697795200077 |
| 21 | 3005761292354 |
| 22 | 14711115274258 |
| 23 | 63872848725319 |
| 24 | 313190405733228 |
| 25 | 1369038458461978 |
| 26 | 6723217549168217 |
| 27 | 29561165849692203 |
[1,1,4,10,46,149,690,2497,11744,45062,214536, 853892,4098631,16729527,80801096,335978483, 1630298162,6876922865,33488217825,142893840268, 697795200077,3005761292354,14711115274258, 63872848725319,313190405733228,1369038458461978, 6723217549168217,29561165849692203] |