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Nth term of 3,11,25,45

1 Answer

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3n^2 - n - 2. So nth term of 3,11,25,45, ... is 3 + (3n^2 - n - 2), or simply 3n^2 - n + 1. Check: put say, n=5 into it and get 75 - 5 + 1 = 71 which checks with the 5th term of 3,11,25,45,71,103, ...
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