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Search: id:A101530
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| A101530 |
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Indices of primes in sequence defined by A(0) = 69, A(n) = 10*A(n-1) - 41 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 (580*10^n + 41)/9 is prime.
Numbers n such that digit 6 followed by n >= 0 occurrences of digit 4 followed by digit 9 is prime.
Numbers corresponding to terms <= 698 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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LINKS
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Makoto Kamada, Factorizations of near-repdigit numbers.
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EXAMPLE
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6449 is prime, hence 2 is a term.
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PROGRAM
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(PARI) a=69; for(n=0, 1000, if(isprime(a), print1(n, ", ")); a=10*a-41)
(PARI) for(n=0, 1000, if(isprime((580*10^n+41)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A103037(n) - 1.
Adjacent sequences: A101527 A101528 A101529 this_sequence A101531 A101532 A101533
Sequence in context: A111012 A055693 A106299 this_sequence A001184 A098653 A119433
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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 06 2004
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EXTENSIONS
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5714 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
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