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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 25 |
| 4 | 100 |
| 5 | 398 |
| 6 | 1652 |
| 7 | 6956 |
| 8 | 29787 |
| 9 | 128925 |
| 10 | 563042 |
| 11 | 2478992 |
| 12 | 10987489 |
| 13 | 48981786 |
| 14 | 219416367 |
| 15 | 987118004 |
| 16 | 4458156696 |
| 17 | 20203631329 |
| 18 | 91841898320 |
| 19 | 418644067776 |
| 20 | 1913128048163 |
| 21 | 8762818322115 |
| 22 | 40221642374777 |
| 23 | 184976329216192 |
| 24 | 852212015882142 |
| 25 | 3932780978049604 |
| 26 | 18176976409015648 |
| 27 | 84133167344160970 |
[1,2,7,25,100,398,1652,6956,29787,128925,563042, 2478992,10987489,48981786,219416367,987118004, 4458156696,20203631329,91841898320,418644067776, 1913128048163,8762818322115,40221642374777, 184976329216192,852212015882142,3932780978049604, 18176976409015648,84133167344160970] |