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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 4 |
| 4 | 19 |
| 5 | 49 |
| 6 | 100 |
| 7 | 316 |
| 8 | 766 |
| 9 | 1883 |
| 10 | 5221 |
| 11 | 12797 |
| 12 | 33376 |
| 13 | 86922 |
| 14 | 220743 |
| 15 | 573264 |
| 16 | 1477256 |
| 17 | 3792956 |
| 18 | 9804491 |
| 19 | 25237000 |
| 20 | 64989265 |
| 21 | 167646836 |
| 22 | 431649191 |
| 23 | 1112482352 |
| 24 | 2866999890 |
| 25 | 7385967351 |
| 26 | 19033926173 |
| 27 | 49045740426 |
| 28 | 126371267386 |
[1,4,4,19,49,100,316,766,1883,5221,12797,33376, 86922,220743,573264,1477256,3792956,9804491, 25237000,64989265,167646836,431649191,1112482352, 2866999890,7385967351,19033926173,49045740426, 126371267386] |