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A083821
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Primes in which odd positioned digits are composite and even positioned digits are primes. The least significant digit is the taken to be the first digit.
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1
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29, 59, 79, 439, 479, 659, 829, 839, 859, 929, 2459, 2659, 2879, 2939, 3659, 3929, 5479, 5639, 5659, 5839, 5879, 5939, 7459, 7639, 7829, 7879, 42829, 42839, 42859, 42929, 42979, 45439, 45659, 45959, 45979, 47459, 47629, 47639, 47659, 47939
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OFFSET
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1,1
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COMMENTS
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Terms are == 9 (mod 10).
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LINKS
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Table of n, a(n) for n=1..40.
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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 (! iscomp(rd[i]), return (0)), if (! isprime(rd[i]), return (0))); ); return (1); } \\ Michel Marcus, Apr 20 2014
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CROSSREFS
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Cf. A083820.
Sequence in context: A080170 A078848 A055784 * A042666 A042668 A042664
Adjacent sequences: A083818 A083819 A083820 * A083822 A083823 A083824
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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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More terms from Ray Chandler, May 20 2003
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STATUS
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approved
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