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Search: id:A101840
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| A101840 |
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Indices of primes in sequence defined by A(0) = 37, A(n) = 10*A(n-1) - 3 for n > 0. |
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+0
1
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| 0, 1, 11, 14, 50, 193, 497, 2135, 2821, 3761, 7427
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Numbers n such that (330*10^n + 3)/9 is prime.
Numbers n such that digit 3 followed by n >= 0 occurrences of digit 6 followed by digit 7 is prime.
Numbers corresponding to terms <= 497 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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367 is prime, hence 1 is a term.
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PROGRAM
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(PARI) a=37; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-3)
(PARI) for(n=0, 1500, if(isprime((330*10^n+3)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A102975(n) - 1.
Sequence in context: A045139 A043105 A043885 this_sequence A061087 A063964 A139065
Adjacent sequences: A101837 A101838 A101839 this_sequence A101841 A101842 A101843
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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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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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