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A101737
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Indices of primes in sequence defined by A(0) = 49, A(n) = 10*A(n-1) - 1 for n > 0.
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0
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2, 3, 5, 9, 11, 17, 39, 47, 95, 105, 113, 143, 363, 617, 1089
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Numbers n such that (440*10^n + 1)/9 is prime.
Numbers n such that digit 4 followed by n >= 0 occurrences of digit 8 followed by digit 9 is prime.
Numbers corresponding to terms <= 617 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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EXAMPLE
| 4889 is prime, hence 2 is a term.
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PROG
| (PARI) a=49; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-1)
(PARI) for(n=0, 1500, if(isprime((440*10^n+1)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
a(n) = A103000(n) - 1.
Sequence in context: A195668 A059042 A157604 * A176550 A019276 A097683
Adjacent sequences: A101734 A101735 A101736 * A101738 A101739 A101740
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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 14 2004
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