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A038692
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Square numbers that are concatenations of two or more prime numbers.
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6
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25, 225, 289, 361, 529, 729, 2401, 2601, 2809, 4761, 5329, 5929, 7225, 7569, 11449, 11881, 13225, 15129, 19881, 21609, 22801, 23409, 24649, 25281, 26569, 27225, 29241, 29929, 31329, 32761, 34969, 36481, 39601, 47961, 52441, 53361, 54289, 55225, 57121, 58081
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listen;
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internal format)
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OFFSET
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1,1
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LINKS
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FORMULA
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MATHEMATICA
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ric[d_] := PrimeQ@ FromDigits@ d || AnyTrue[ TakeDrop[d, #] & /@ Range[ Length[d] - 1], #[[2, 1]] > 0 && PrimeQ@ FromDigits@ #[[1]] && ric@ #[[2]] &]; ok[n_] := If[ EvenQ[n] && Mod[n, 10] != 2, False, ric@ IntegerDigits@ n]; Select[ Range[300]^2, ok] (* Giovanni Resta, Mar 16 2020 *)
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PROG
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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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EXTENSIONS
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STATUS
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approved
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