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A082445
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Palindromic primes with middle digit 9.
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1
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191, 797, 13931, 17971, 19991, 71917, 77977, 79997, 94949, 95959, 1129211, 1409041, 1469641, 1489841, 1579751, 1589851, 1609061, 1829281, 1879781, 1909091, 1969691, 3089803, 3319133, 3329233, 3439343, 3449443, 3479743, 3569653, 3589853, 3689863, 3709073, 3769673
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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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MATHEMATICA
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ppmd9Q[n_]:=Module[{idn=IntegerDigits[n]}, idn==Reverse[idn]&&idn[[(Length[ idn]+1)/2]]==9]; Flatten[Table[Select[Prime[Range[PrimePi[10^(2n)+1], PrimePi[ 10^(2n+1)-1]]], ppmd9Q], {n, 3}]] (* Harvey P. Dale, Feb 11 2015 *)
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PROG
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(Magma) [ p: p in PrimesUpTo(200000000) | IsOdd(d) and D[(d+1) div 2] eq 9 and D eq Reverse(D) where d is #D where D is Intseq(p) ]; // Vincenzo Librandi, Apr 12 2011
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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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