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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 0 |
| 3 | 10 |
| 4 | 12 |
| 5 | 50 |
| 6 | 100 |
| 7 | 298 |
| 8 | 700 |
| 9 | 1890 |
| 10 | 4692 |
| 11 | 12250 |
| 12 | 31020 |
| 13 | 80018 |
| 14 | 204100 |
| 15 | 524170 |
| 16 | 1340572 |
| 17 | 3437250 |
| 18 | 8799540 |
| 19 | 22548538 |
| 20 | 57746700 |
| 21 | 147940850 |
| 22 | 378927652 |
| 23 | 970691050 |
| 24 | 2486401660 |
| 25 | 6369165858 |
| 26 | 16314772500 |
| 27 | 41791435930 |
| 28 | 107050525932 |
| 29 | 274216269650 |
| 30 | 702418373380 |
| 31 | 1799283451978 |
[4,0,10,12,50,100,298,700,1890,4692,12250,31020, 80018,204100,524170,1340572,3437250,8799540, 22548538,57746700,147940850,378927652,970691050, 2486401660,6369165858,16314772500,41791435930, 107050525932,274216269650,702418373380, 1799283451978] |