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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 21 |
| 4 | 78 |
| 5 | 302 |
| 6 | 1229 |
| 7 | 5080 |
| 8 | 21463 |
| 9 | 92119 |
| 10 | 399231 |
| 11 | 1749148 |
| 12 | 7722728 |
| 13 | 34318206 |
| 14 | 153446902 |
| 15 | 689417576 |
| 16 | 3111064995 |
| 17 | 14094596300 |
| 18 | 64068297724 |
| 19 | 292131774074 |
| 20 | 1335704254532 |
| 21 | 6122228060771 |
| 22 | 28125255700415 |
| 23 | 129471436761531 |
| 24 | 597128880391576 |
| 25 | 2758783273430833 |
| 26 | 12766134349205890 |
| 27 | 59162217237598623 |
[1,2,6,21,78,302,1229,5080,21463,92119,399231, 1749148,7722728,34318206,153446902,689417576, 3111064995,14094596300,64068297724,292131774074, 1335704254532,6122228060771,28125255700415, 129471436761531,597128880391576,2758783273430833, 12766134349205890,59162217237598623] |