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Search: id:A101827
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| A101827 |
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Indices of primes in sequence defined by A(0) = 39, A(n) = 10*A(n-1) - 71 for n > 0. |
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1
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OFFSET
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1,1
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COMMENT
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Numbers n such that (280*10^n + 71)/9 is prime.
Numbers n such that digit 3 followed by n >= 0 occurrences of digit 1 followed by digit 9 is prime.
Numbers corresponding to terms <= 796 are certified primes.
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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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EXAMPLE
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3119 is prime, hence 2 is a term.
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PROGRAM
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(PARI) a=39; for(n=0, 3200, if(isprime(a), print1(n, ", ")); a=10*a-71)
(PARI) for(n=0, 3200, if(isprime((280*10^n+71)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A102965(n) - 1.
Sequence in context: A140898 A120814 A115890 this_sequence A163275 A157073 A103207
Adjacent sequences: A101824 A101825 A101826 this_sequence A101828 A101829 A101830
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KEYWORD
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nonn,hard,more
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AUTHOR
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Klaus Brockhaus (klaus-brockhaus(AT)t-online.de) and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 20 2004
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