Let be a positive real number. A positive integer will be called -squarish if it is the product of two integers and such that . Prove that there are infinitely many occurrences of six consecutive -squarish integers.
, 2014
Solution
If is a large enough positive integer, then and are both -squarish. Next, if is a large enough positive integer and , then , and are all three -squarish. Finally, if is a large enough positive integer and , then is -squarish.
Consequently, , , , are six consecutive -squarish integers, provided that , where and are sufficiently large integers. To conclude, write to turn the condition into a Pell equation, , which has arbitrarily large solutions,
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