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A101583
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Indices of primes in sequence defined by A(0) = 59, A(n) = 10*A(n-1) - 21 for n > 0.
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0
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0, 1, 2, 9, 24, 28, 33, 72, 75, 76, 650, 883, 937, 1251, 1892, 3341, 4033, 6167, 6215, 6230, 6811, 11045, 15447, 16627, 16917, 18733
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Numbers n such that (510*10^n + 21)/9 is prime.
Numbers n such that digit 5 followed by n >= 0 occurrences of digit 6 followed by digit 9 is prime.
Numbers corresponding to terms <= 937 are certified primes.
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REFERENCES
| Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
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LINKS
| Makoto Kamada, Factorizations of near-repdigit numbers.
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EXAMPLE
| 5669 is prime, hence 2 is a term.
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PROG
| (PARI) a=59; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-21)
(PARI) for(n=0, 1500, if(isprime((510*10^n+21)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
a(n) = A103018(n) - 1.
Sequence in context: A091107 A133469 A075714 * A204556 A185669 A006002
Adjacent sequences: A101580 A101581 A101582 * A101584 A101585 A101586
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KEYWORD
| nonn,more
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AUTHOR
| 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
| 7 additional terms, corresponding to probable primes, from Ryan Propper (rpropper(AT)stanford.edu), Jun 24 2005. Next term after 6811 is greater than 10,000.
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
Edited by T. D. Noe (noe(AT)sspectra.com), Oct 30 2008
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