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Search: id:A065726
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| A065726 |
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Primes p such that the decimal expansion of its base 8 conversion is also prime. |
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+0
2
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| 2, 3, 5, 7, 11, 19, 31, 43, 59, 67, 71, 89, 137, 151, 179, 191, 199, 223, 251, 257, 281, 283, 307, 311, 337, 353, 359, 367, 383, 409, 419, 433, 443, 449, 523, 563, 617, 619, 641, 659, 727, 787, 809, 811, 857, 887, 907, 919, 947, 977, 1033, 1039, 1097, 1123
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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In general rebase notation (Marc LeBrun): p(n) = (8) [p] (10).
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,1000
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EXAMPLE
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E.g. 787{10} = 1423{8} is prime but also 1423{10}.
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MATHEMATICA
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Select[ Range[2500], PrimeQ[ # ] && PrimeQ[ FromDigits[ IntegerDigits[ #, 8]]] & ]
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PROGRAM
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(PARI) baseE(x, b)= { local(d, e=0, f=1); while (x>0, d=x-b*(x\b); x\=b; e+=d*f; f*=10); return(e) } { n=0; for (m=1, 10^9, p=prime(m); b=baseE(p, 8); if (isprime(b), write("b065726.txt", n++, " ", p); if (n==1000, return)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Oct 28 2009]
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CROSSREFS
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Cf. A065720 up to A065727, A065361.
Sequence in context: A115617 A003064 A057429 this_sequence A118985 A089769 A033274
Adjacent sequences: A065723 A065724 A065725 this_sequence A065727 A065728 A065729
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KEYWORD
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nonn,base,new
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AUTHOR
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Patrick De Geest (pdg(AT)worldofnumbers.com), Nov 15 2001.
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