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A101524
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Indices of primes in sequence defined by A(0) = 69, A(n) = 10*A(n-1) - 61 for n > 0.
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0
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OFFSET
| 1,1
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COMMENTS
| Numbers n such that (560*10^n + 61)/9 is prime.
Numbers n such that digit 6 followed by n >= 0 occurrences of digit 2 followed by digit 9 is prime.
Numbers corresponding to terms <= 338 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
| 6229 is prime, hence 2 is a term.
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MATHEMATICA
| #-1&/@Transpose[Select[NestList[{First[#]+1, 10Last[#]-61}&, {1, 69}, 2000], PrimeQ[Last[#]]&]][[1]] (* From Harvey P. Dale, Aug 15 2011 *)
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PROG
| (PARI) a=69; for(n=0, 1000, if(isprime(a), print1(n, ", ")); a=10*a-61)
(PARI) for(n=0, 1000, if(isprime((560*10^n+61)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
a(n) = A103031(n) - 1.
Sequence in context: A180605 A094155 A132626 * A013039 A011809 A102596
Adjacent sequences: A101521 A101522 A101523 * A101525 A101526 A101527
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KEYWORD
| nonn,bref,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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