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Search: id:A101138
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| A101138 |
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Indices of primes in sequence defined by A(0) = 79, A(n) = 10*A(n-1) - 51 for n > 0. |
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+0
1
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| 0, 1, 4, 6, 84, 344, 1594, 2104, 6385, 9118, 9331
(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 (660*10^n + 51)/9 is prime.
Numbers n such that digit 7 followed by n >= 0 occurrences of digit 3 followed by digit 9 is prime.
Numbers corresponding to terms <= 344 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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733339 is prime, hence 4 is a term.
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PROGRAM
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(PARI) a=79; for(n=0, 1000, if(isprime(a), print1(n, ", ")); a=10*a-51)
(PARI) for(n=0, 1000, if(isprime((660*10^n+51)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A103056(n) - 1.
Sequence in context: A058163 A013127 A012970 this_sequence A012897 A013079 A087934
Adjacent sequences: A101135 A101136 A101137 this_sequence A101139 A101140 A101141
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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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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
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