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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 32 |
| 3 | 139 |
| 4 | 678 |
| 5 | 3182 |
| 6 | 15199 |
| 7 | 72514 |
| 8 | 346244 |
| 9 | 1653214 |
| 10 | 7893443 |
| 11 | 37688062 |
| 12 | 179946317 |
| 13 | 859175558 |
| 14 | 4102237937 |
| 15 | 19586633161 |
| 16 | 93518758201 |
| 17 | 446516665710 |
| 18 | 2131948036306 |
| 19 | 10179244758257 |
| 20 | 48602040050313 |
| 21 | 232056341426270 |
| 22 | 1107981178164225 |
[4,32,139,678,3182,15199,72514,346244,1653214, 7893443,37688062,179946317,859175558,4102237937, 19586633161,93518758201,446516665710, 2131948036306,10179244758257,48602040050313, 232056341426270,1107981178164225] |