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A179444
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Composite numbers m of the form m = 10k + 1 where k is also composite.
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2
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81, 91, 121, 141, 161, 201, 221, 261, 301, 321, 341, 351, 361, 381, 391, 441, 451, 481, 501, 511, 551, 561, 581, 621, 651, 681, 721, 741, 771, 781, 801, 841, 851, 861, 871, 901, 921, 931, 951, 961, 981, 1001, 1041, 1081, 1101, 1111, 1121, 1141, 1161, 1191, 1211, 1221, 1241, 1251, 1261, 1281, 1331
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OFFSET
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1,1
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COMMENTS
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Corresponding values of k in A179443.
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LINKS
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MAPLE
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select(t -> not isprime((t-1)/10) and not isprime(t), [seq(i, i=21..10001, 10)]); # Robert Israel, Jun 11 2019
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MATHEMATICA
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Select[10#+1&/@Select[Range[100], !PrimeQ[#]&], !PrimeQ[#]&] (* Harvey P. Dale, Dec 01 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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EXTENSIONS
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STATUS
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approved
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