Question 548588: write the equivalence for series 1,3,5,7,11,13...
Answer by KMST(5328)   (Show Source):
You can put this solution on YOUR website! Did you skip a 9 in there? As written it is not a sequence/series that you would expect. It's like finding that the correct answer to "miss America" in a Jeopardy game is "If the USSR sent an intercontinental ballistic missile aimed at the US, what would you hope it would do?"
I would expect 1, 3, 5, 7, 9, 11, 13, ..., which I would call an arithmetic sequence (not a series), and it includes that 9, between the 7 and the 11. That would make it an arithmetic sequence with a common difference of 2 (where each number is the previous one plus 2).
I would describe it with the recursive formula  with 
I could also use an explicit formula, such as
 or 
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