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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 13 |
| 4 | 53 |
| 5 | 181 |
| 6 | 797 |
| 7 | 2903 |
| 8 | 12859 |
| 9 | 50331 |
| 10 | 225839 |
| 11 | 906225 |
| 12 | 4129853 |
| 13 | 17040887 |
| 14 | 77913159 |
| 15 | 326996909 |
| 16 | 1510147553 |
| 17 | 6422569359 |
| 18 | 29747117651 |
| 19 | 128073608665 |
| 20 | 596327616089 |
| 21 | 2588195705585 |
| 22 | 12089363646993 |
| 23 | 52920358776527 |
| 24 | 247883718872023 |
| 25 | 1091627109014907 |
| 26 | 5127795371773655 |
| 27 | 22715769475682537 |
[1,1,5,13,53,181,797,2903,12859,50331,225839, 906225,4129853,17040887,77913159,326996909, 1510147553,6422569359,29747117651,128073608665, 596327616089,2588195705585,12089363646993, 52920358776527,247883718872023,1091627109014907, 5127795371773655,22715769475682537] |