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Search: id:A101131
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| A101131 |
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Indices of primes in sequence defined by A(0) = 73, A(n) = 10*A(n-1) - 17 for n > 0. |
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1
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OFFSET
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1,2
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COMMENT
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Numbers n such that (640*10^n + 17)/9 is prime.
Numbers n such that digit 7 followed by n >= 0 occurrences of digit 1 followed by digit 3 is prime.
Numbers corresponding to terms <= 937 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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71111113 is prime, hence 6 is a term.
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PROGRAM
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(PARI) a=73; for(n=0, 1000, if(isprime(a), print1(n, ", ")); a=10*a-17)
(PARI) for(n=0, 1000, if(isprime((640*10^n+17)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A103050(n) - 1.
Sequence in context: A137038 A024276 A137037 this_sequence A009688 A132872 A152289
Adjacent sequences: A101128 A101129 A101130 this_sequence A101132 A101133 A101134
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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 03 2004
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