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A101018
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Indices of primes in sequence defined by A(0) = 97, A(n) = 10*A(n-1) + 17 for n > 0.
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0
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0, 2, 3, 5, 8, 11, 15, 33, 128, 242, 251, 528, 4884, 6362
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Numbers n such that (890*10^n - 17)/9 is prime.
Numbers n such that digit 9 followed by n >= 0 occurrences of digit 8 followed by digit 7 is prime.
Numbers corresponding to terms <= 528 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
| 9888887 is prime, hence 5 is a term.
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PROG
| (PARI) a=97; for(n=0, 1000, if(isprime(a), print1(n, ", ")); a=10*a+17)
(PARI) for(n=0, 1000, if(isprime((890*10^n-17)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
a(n) = A103109(n) - 1.
Sequence in context: A125811 A071424 A008762 * A006336 A175831 A070228
Adjacent sequences: A101015 A101016 A101017 * A101019 A101020 A101021
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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), Nov 27 2004
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EXTENSIONS
| More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
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