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A086924
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Primes such that sum of the first and last digits is a square.
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1
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2, 13, 31, 79, 97, 103, 113, 163, 173, 193, 227, 257, 277, 311, 331, 613, 643, 653, 673, 683, 709, 719, 739, 769, 811, 821, 881, 907, 937, 947, 967, 977, 997, 1013, 1033, 1063, 1093, 1103, 1123, 1153, 1163, 1193, 1213, 1223
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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fldsQ[n_]:=Module[{idn=IntegerDigits[n]}, IntegerQ[Sqrt[ idn[[1]] + idn[[-1]]]]]; Select[Prime[Range[200]], fldsQ] (* Harvey P. Dale, Aug 12 2017 *)
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PROG
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(PARI) okdigs(n) = digs = digits(n); issquare(digs[1]+digs[#digs]);
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CROSSREFS
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KEYWORD
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easy,nonn,base
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AUTHOR
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STATUS
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approved
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