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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 9 |
| 4 | 34 |
| 5 | 103 |
| 6 | 379 |
| 7 | 1309 |
| 8 | 4922 |
| 9 | 18125 |
| 10 | 69547 |
| 11 | 265723 |
| 12 | 1038766 |
| 13 | 4073721 |
| 14 | 16165622 |
| 15 | 64471827 |
| 16 | 259161978 |
| 17 | 1047151561 |
| 18 | 4255482729 |
| 19 | 17363577413 |
| 20 | 71174281416 |
| 21 | 292805890291 |
| 22 | 1209181501440 |
| 23 | 5008416381237 |
| 24 | 20807946320760 |
| 25 | 86679404708181 |
| 26 | 362031195792493 |
| 27 | 1515620560170121 |
| 28 | 6358794868736378 |
[1,1,4,9,34,103,379,1309,4922,18125,69547,265723, 1038766,4073721,16165622,64471827,259161978, 1047151561,4255482729,17363577413,71174281416, 292805890291,1209181501440,5008416381237, 20807946320760,86679404708181,362031195792493, 1515620560170121,6358794868736378] |