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A083820
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Primes in which odd positioned digits are prime and even positioned digits are composite. The least significant digit is taken to be the first digit.
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1
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2, 3, 5, 7, 43, 47, 67, 83, 97, 263, 283, 293, 347, 367, 383, 397, 547, 563, 587, 593, 743, 787, 797, 4243, 4283, 4297, 4363, 4397, 4547, 4567, 4583, 4597, 4783, 4787, 4793, 6247, 6263, 6287, 6343, 6367, 6397, 6547, 6563, 6763, 6793, 8243, 8263, 8287, 8293
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OFFSET
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1,1
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COMMENTS
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Primes with prime and composite digits interlaced (starting at the right). - Zak Seidov, Apr 20 2014
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LINKS
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PROG
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(PARI) iscomp(n) = (n != 0) && (n != 1) && ! isprime(n);
isok(p) = {if (! isprime(p), return (0)); rd = digits(subst(Polrev(digits(p)), x, 10)); for (i=1, #rd, if (i % 2, if (! isprime(rd[i]), return (0)), if (! iscomp(rd[i]), return (0))); ); return (1); } \\ Michel Marcus, Apr 20 2014
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 08 2003
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EXTENSIONS
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STATUS
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approved
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