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Search: id:A101575
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| A101575 |
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Indices of primes in sequence defined by A(0) = 57, A(n) = 10*A(n-1) - 43 for n > 0. |
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+0
1
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| 2, 4, 32, 47, 58, 59, 73, 125, 176, 227, 637, 1303, 1643, 2434, 4373, 8749
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Numbers n such that (470*10^n + 43)/9 is prime.
Numbers n such that digit 5 followed by n >= 0 occurrences of digit 2 followed by digit 7 is prime.
Numbers corresponding to terms <= 637 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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522227 is prime, hence 4 is a term.
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PROGRAM
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(PARI) a=57; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-43)
(PARI) for(n=0, 1500, if(isprime((470*10^n+43)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A103010(n) - 1.
Sequence in context: A082913 A083205 A019542 this_sequence A009098 A133127 A122693
Adjacent sequences: A101572 A101573 A101574 this_sequence A101576 A101577 A101578
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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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