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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 9 |
| 4 | 39 |
| 5 | 112 |
| 6 | 514 |
| 7 | 1664 |
| 8 | 7833 |
| 9 | 27346 |
| 10 | 130723 |
| 11 | 479977 |
| 12 | 2317526 |
| 13 | 8827710 |
| 14 | 42919942 |
| 15 | 168085941 |
| 16 | 821366455 |
| 17 | 3287613734 |
| 18 | 16126250115 |
| 19 | 65690433233 |
| 20 | 323170950475 |
| 21 | 1335621327595 |
| 22 | 6586014226736 |
| 23 | 27550903813319 |
| 24 | 136109790047564 |
| 25 | 575278188394020 |
| 26 | 2846407705761070 |
| 27 | 12137734111711302 |
| 28 | 60132476045010784 |
[1,1,4,9,39,112,514,1664,7833,27346,130723,479977, 2317526,8827710,42919942,168085941,821366455, 3287613734,16126250115,65690433233,323170950475, 1335621327595,6586014226736,27550903813319, 136109790047564,575278188394020,2846407705761070, 12137734111711302,60132476045010784] |