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A167720
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Squares that become a prime number when prefixed with a 5.
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1
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9, 441, 1521, 12321, 19881, 29241, 59049, 74529, 95481, 123201, 168921, 199809, 227529, 263169, 288369, 328329, 356409, 370881, 385641, 471969, 480249, 488601, 531441, 558009, 594441, 603729, 613089, 622521, 690561, 741321, 804609, 826281
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OFFSET
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1,1
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COMMENTS
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LINKS
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MATHEMATICA
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Select[Range[1, 500, 2]^2, PrimeQ[FromDigits[Join[{5}, IntegerDigits[#]]]] &] (* G. C. Greubel, Jun 20 2016 *)
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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STATUS
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approved
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