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| n | a(n) |
|---|---|
| 1 | 220 |
| 2 | 479 |
| 3 | 1857 |
| 4 | 5998 |
| 5 | 20408 |
| 6 | 71846 |
| 7 | 245486 |
| 8 | 841296 |
| 9 | 2905978 |
| 10 | 9992478 |
| 11 | 34348500 |
| 12 | 118254574 |
| 13 | 406871094 |
| 14 | 1399624310 |
| 15 | 4816056622 |
| 16 | 16570641810 |
| 17 | 57011471540 |
| 18 | 196158495144 |
| 19 | 674916008534 |
| 20 | 2322129167778 |
| 21 | 7989626498572 |
| 22 | 27489503304114 |
[220,479,1857,5998,20408,71846,245486,841296, 2905978,9992478,34348500,118254574,406871094, 1399624310,4816056622,16570641810,57011471540, 196158495144,674916008534,2322129167778, 7989626498572,27489503304114] |