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Search: id:A056252
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| A056252 |
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Indices of primes in sequence defined by A(0) = 33, A(n) = 10*A(n-1) - 7 for n > 0. |
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+0
2
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OFFSET
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1,1
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COMMENT
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Numbers n such that (290*10^n + 7)/9 is prime.
Numbers n such that the digit 3 followed by n >= 0 occurrences of the digit 2 followed by the digit 3 is prime.
Numbers corresponding to terms <= 893 are certified primes.
a(n) = A082705(n-1) - 2.
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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 322...223.
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EXAMPLE
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3222223 is prime, hence 5 is a term.
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PROGRAM
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(PARI) a=33; for(n=0, 1600, if(isprime(a), print1(n, ", ")); a=10*a-7)
(PARI) for(n=0, 1600, if(isprime((290*10^n+7)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275, A082705.
Sequence in context: A114363 A083687 A101829 this_sequence A090817 A011496 A140249
Adjacent sequences: A056249 A056250 A056251 this_sequence A056253 A056254 A056255
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KEYWORD
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nonn,hard,more
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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), Dec 20 2004
Edited by njas, Apr 17 2007
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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