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A171995
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Twin natural nonprimes with nonprime number of prime factors.
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0
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1, 625, 1715, 1925, 2125, 2875, 2975, 3575, 3773, 4165, 4225, 4235, 4625, 5125, 5375, 5425, 5635, 5831, 5875, 5915, 6517, 6625, 7007, 7225, 7315, 7375, 7595, 7625, 7735, 7889, 7975, 8075, 8225, 8281, 8855, 8875, 9025, 9425, 9775, 9875, 10045, 10075
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OFFSET
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1,2
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COMMENTS
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LINKS
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EXAMPLE
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a(1)=1(without prime factors), a(2)=625(=5*5*5*5), a(3)=1715(=5*7*7*7).
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PROG
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(PARI) isA171995(n)=n>0&!isprime(n)&((n%6==1&!isprime(n-2))||(n%6==5&!isprime(n+2)))&!isprime(bigomega(n))
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CROSSREFS
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KEYWORD
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nonn,less,changed
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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