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A219998
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Prime-free decades such that the previous decade is also prime-free.
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2
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114, 134, 135, 168, 219, 249, 315, 324, 348, 375, 419, 431, 477, 485, 513, 525, 537, 546, 561, 576, 597, 641, 651, 675, 693, 709, 714, 727, 738, 777, 798, 834, 840, 848, 849, 891, 908, 936, 945, 957, 999, 1002, 1005, 1038, 1041, 1081, 1082, 1092, 1134, 1176
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OFFSET
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1,1
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COMMENTS
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Numbers n such that 10n-9, 10n-7, 10n-3, 10n-1, 10n+1, 10n+3, 10n+7, and 10n+9 are composite.
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LINKS
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FORMULA
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a(n) ~ n.
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PROG
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(PARI) for(i=2, 1200, if(isprime(10*i-9)==0&&isprime(10*i-7)==0&&isprime(10*i-3)==0&&isprime(10*i-1)==0&&isprime(10*i+1)==0&&isprime(10*i+3)==0&&isprime(10*i+7)==0&&isprime(10*i+9)==0, print1(i", ")))
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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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STATUS
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approved
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