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Hi,

I recently became interested in some number theoretical questions. I have actually never really studied it before so my question might be really easy to answer.

I was trying to determine for which values of [itex]k[/itex] the number [itex]10^k+1[/itex] is divisible by a square. (http://www.research.att.com/~njas/sequences/A086982" [Broken]). The smallest such [itex]k[/itex] is 11 with the corresponding square being [itex]121=11^2[/itex]. Is it a coincidence that the number 11 occurs twice here? Is there anything more to say about this sequence?

Thanks for any hints or tips on how to start a problem like that.

Pere

I recently became interested in some number theoretical questions. I have actually never really studied it before so my question might be really easy to answer.

I was trying to determine for which values of [itex]k[/itex] the number [itex]10^k+1[/itex] is divisible by a square. (http://www.research.att.com/~njas/sequences/A086982" [Broken]). The smallest such [itex]k[/itex] is 11 with the corresponding square being [itex]121=11^2[/itex]. Is it a coincidence that the number 11 occurs twice here? Is there anything more to say about this sequence?

Thanks for any hints or tips on how to start a problem like that.

Pere

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