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A101529
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Indices of primes in sequence defined by A(0) = 67, A(n) = 10*A(n-1) - 23 for n > 0.
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0
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0, 1, 4, 9, 39, 46, 57, 72, 91, 112, 123, 129, 886, 1233, 1537, 2062, 2590, 2785, 3144
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Numbers n such that (580*10^n + 23)/9 is prime.
Numbers n such that digit 6 followed by n >= 0 occurrences of digit 4 followed by digit 7 is prime.
Numbers corresponding to terms <= 886 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
| 647 is prime, hence 1 is a term.
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PROG
| (PARI) a=67; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-23)
(PARI) for(n=0, 1500, if(isprime((580*10^n+23)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
a(n) = A103036(n) - 1.
Sequence in context: A149151 A149152 A149153 * A149154 A149155 A149156
Adjacent sequences: A101526 A101527 A101528 * A101530 A101531 A101532
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KEYWORD
| nonn,hard,more
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AUTHOR
| Klaus Brockhaus (klaus-brockhaus(AT)t-online.de) and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 06 2004
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EXTENSIONS
| More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
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