Find the rule 1 + 1.2 + 3.3 + 5.1 + 7.2 + 9.3 + 11.1 + 13, 2 + 15. What's the 80th formula? How many formula is 1 + 73?
The 80th formula is 2 + 159
1 + 73 is the 37th formula
Each formula is divided into two parts, the first part is 1.2.3 reciprocating cycle; the second part is 1.3.5.7... Odd increasing
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