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A175983
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Squares n^2 that become prime after omitting all ones in their decimal expansion.
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0
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121, 1089, 11449, 21609, 31329, 56169, 117649, 127449, 131769, 139129, 142129, 154449, 178929, 199809, 431649, 471969, 751689, 1014049, 1159929, 1172889, 1194649, 1530169, 1841449, 2211169, 2411809, 2518569, 2634129, 3108169, 3143529
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OFFSET
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1,1
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COMMENTS
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Corresponding values of n are 11, 33, 107, 147, 177, 237, 343, 357, 363, 373, 377, 393, 423, 447, 657, 687, 867, 1007, 1077, 1083, ....
The resulting primes are 2, 89, 449, 2609, 3329, 5669, 7649, 27449, 3769, 3929, 4229, 54449, 78929, 99809, 43649, 47969, 75689, ....
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LINKS
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MATHEMATICA
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Reap[Do[If[PrimeQ[FromDigits[DeleteCases[IntegerDigits[n^2], 1]]], Sow[n^2]], {n, 5000}]][[2, 1]]
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PROG
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(Magma) remove1:=func< n | [ d: d in n | d ne 1 ] >; [ s: n in [1..3400] | IsPrime(Seqint(remove1(Intseq(s)))) where s is n^2 ];
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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