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A102027
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Indices of primes in sequence defined by A(0) = 13, A(n) = 10*A(n-1) + 43 for n > 0.
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1
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OFFSET
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1,3
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COMMENTS
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Numbers n such that (160*10^n - 43)/9 is prime.
Numbers n such that digit 1 followed by n >= 0 occurrences of digit 7 followed by digit 3 is prime.
Numbers corresponding to terms <= 184 are certified primes.
a(11) > 10^5. - Robert Price, Feb 11 2015
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REFERENCES
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Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
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LINKS
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Table of n, a(n) for n=1..10.
Makoto Kamada, Prime numbers of the form 177...773.
Index entries for primes involving repunits.
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FORMULA
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a(n) = A102942(n) - 1.
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EXAMPLE
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173 is prime, hence 1 is a term.
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PROG
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(PARI) a=13; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+43)
(PARI) for(n=0, 1500, if(isprime((160*10^n-43)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275, A102942.
Sequence in context: A294459 A075927 A119617 * A031294 A147129 A173825
Adjacent sequences: A102024 A102025 A102026 * A102028 A102029 A102030
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KEYWORD
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nonn,hard,more
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AUTHOR
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Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 28 2004
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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
a(10) from Robert Price, Feb 11 2015
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STATUS
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approved
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