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A158019
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Numbers such that (n-1)/2 and 10*n-1 are both prime.
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0
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11, 15, 23, 27, 35, 39, 83, 107, 123, 143, 167, 179, 195, 203, 207, 227, 255, 275, 279, 347, 399, 423, 455, 479, 567, 587, 623, 627, 695, 707, 735, 759, 767, 779, 795, 839, 843, 863, 867, 935, 975, 983, 1007, 1043, 1095, 1115, 1155, 1215, 1227, 1283, 1323
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OFFSET
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1,1
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COMMENTS
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Relating the two prime types:
(p-1)/2,(p-1)/4,(p-1)/6,(p-1)/8,(p-1)/10,(p-1)/12...
and
2*p-1,4*p-1,6*p-1,8*p-1,10*p-1...
where both contain 11,23 subsequence.
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LINKS
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MATHEMATICA
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Flatten[Table[If[PrimeQ[(n - 1)/2] && PrimeQ[10*n - 1], n, {}], {n, 1, 10000}]]
Select[Range[1, 1500, 2], PrimeQ[(#-1)/2]&&PrimeQ[10#-1]&] (* Harvey P. Dale, Mar 10 2013 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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