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A101586
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Indices of primes in sequence defined by A(0) = 59, A(n) = 10*A(n-1) - 11 for n > 0.
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0
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0, 2, 6, 14, 26, 128, 188, 332, 1323, 1599, 2198, 9999
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Numbers n such that (520*10^n + 11)/9 is prime.
Numbers n such that digit 5 followed by n >= 0 occurrences of digit 7 followed by digit 9 is prime.
Numbers corresponding to terms <= 332 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
| 5779 is prime, hence 2 is a term.
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MATHEMATICA
| Select[Range[0, 10000], PrimeQ[FromDigits[Join[PadRight[{5}, #+1, 7], {9}]]]&] (* From Harvey P. Dale, Jan 28 2012 *)
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PROG
| (PARI) a=59; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-11)
(PARI) for(n=0, 1500, if(isprime((520*10^n+11)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
a(n) = A103021(n) - 1.
Sequence in context: A138318 A068042 A068041 * A178080 A121968 A161212
Adjacent sequences: A101583 A101584 A101585 * A101587 A101588 A101589
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KEYWORD
| nonn
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AUTHOR
| Klaus Brockhaus (klaus-brockhaus(AT)t-online.de) and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 09 2004
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EXTENSIONS
| 1599, 2198, 9999 from Jorge Coveiro (jorgecoveiro(AT)yahoo.com), Dec 27 2005
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