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Search: id:A101584
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| A101584 |
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Indices of primes in sequence defined by A(0) = 51, A(n) = 10*A(n-1) + 61 for n > 0. |
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+0
1
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| 1, 5, 8, 26, 29, 47, 140, 149, 371, 421, 1096, 3569, 4606, 5288
(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 (520*10^n - 61)/9 is prime.
Numbers n such that digit 5 followed by n >= 0 occurrences of digit 7 followed by digit 1 is prime.
Numbers corresponding to terms <= 421 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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571 is prime, hence 1 is a term.
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PROGRAM
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(PARI) a=51; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+61)
(PARI) for(n=0, 1500, if(isprime((520*10^n-61)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A103019(n) - 1.
Sequence in context: A069959 A038250 A067973 this_sequence A112577 A026539 A126700
Adjacent sequences: A101581 A101582 A101583 this_sequence A101585 A101586 A101587
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KEYWORD
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nonn,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 09 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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