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Search: id:A101578
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| A101578 |
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Indices of primes in sequence defined by A(0) = 51, A(n) = 10*A(n-1) + 31 for n > 0. |
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+0
1
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| 1, 2, 85, 133, 184, 343, 395, 475, 833, 1798, 2146, 2417, 5215, 5881, 6215
(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 (490*10^n - 31)/9 is prime.
Numbers n such that digit 5 followed by n >= 0 occurrences of digit 4 followed by digit 1 is prime.
Numbers corresponding to terms <= 833 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 544...441.
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EXAMPLE
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5441 is prime, hence 2 is a term.
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PROGRAM
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(PARI) a=51; for(n=0, 1000, if(isprime(a), print1(n, ", ")); a=10*a+31)
(PARI) for(n=0, 1000, if(isprime((490*10^n-31)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A103013(n) - 1.
Sequence in context: A157315 A163971 A078166 this_sequence A041881 A076542 A066226
Adjacent sequences: A101575 A101576 A101577 this_sequence A101579 A101580 A101581
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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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3 more terms from Ryan Propper (rpropper(AT)stanford.edu), Jun 16 2005
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007
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