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Search: id:A101537
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| A101537 |
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Indices of primes in sequence defined by A(0) = 61, A(n) = 10*A(n-1) + 71 for n > 0. |
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+0
1
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| 0, 3, 9, 12, 177, 303, 330, 501, 743, 1026, 1769, 5304
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Numbers n such that (620*10^n - 71)/9 is prime.
Numbers n such that digit 6 followed by n >= 0 occurrences of digit 8 followed by digit 1 is prime.
Numbers corresponding to terms <= 743 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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68881 is prime, hence 3 is a term.
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PROGRAM
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(PARI) a=61; for(n=0, 1200, if(isprime(a), print1(n, ", ")); a=10*a+71)
(PARI) for(n=0, 1200, if(isprime((620*10^n-71)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A103044(n) - 1.
Sequence in context: A081601 A137344 A029524 this_sequence A070353 A029458 A050571
Adjacent sequences: A101534 A101535 A101536 this_sequence A101538 A101539 A101540
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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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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
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