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A101971
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Indices of primes in sequence defined by A(0) = 27, A(n) = 10*A(n-1) + 17 for n > 0.
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0
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OFFSET
| 1,1
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COMMENTS
| Numbers n such that (260*10^n - 17)/9 is prime.
Numbers n such that digit 2 followed by n >= 0 occurrences of digit 8 followed by digit 7 is prime.
Numbers corresponding to terms <= 454 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
| 2887 is prime, hence 2 is a term.
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PROG
| (PARI) a=27; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+17)
(PARI) for(n=0, 1500, if(isprime((260*10^n-17)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
a(n) = A102962(n) - 1.
Sequence in context: A051625 A056098 A027361 * A162037 A183239 A049774
Adjacent sequences: A101968 A101969 A101970 * A101972 A101973 A101974
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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 23 2004
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EXTENSIONS
| More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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