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Search: id:A056264
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| A056264 |
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Indices of primes in sequence defined by A(0) = 99, A(n) = 10*A(n-1) - 71 for n > 0. |
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1
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OFFSET
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1,2
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COMMENT
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Numbers n such that (820*10^n + 71)/9 is a prime.
Numbers n such that digit 9 followed by n >= 0 occurrences of digit 1 followed by digit 9 is prime.
Numbers corresponding to terms <= 1139 are certified primes. For number corresponding to 10393 see P. De Geest, PDP Reference Table.
a(n) = A082717(n-1) - 2; a(4) = 10393 is based on A082717.
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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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P. De Geest, PDP Reference Table
Makoto Kamada, Factorizations of 911...119.
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EXAMPLE
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919 is prime, hence 1 is a term.
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PROGRAM
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(PARI) a=99; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-71)
(PARI) for(n=0, 1500, if(isprime((820*10^n+71)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275, A082717.
Sequence in context: A129210 A137521 A132830 this_sequence A023097 A098195 A067916
Adjacent sequences: A056261 A056262 A056263 this_sequence A056265 A056266 A056267
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KEYWORD
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nonn,hard,more,less
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 18 2000
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EXTENSIONS
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Additional comments from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de) and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Nov 27 2004
Edited by njas, Jun 15 2007
One more term from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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