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Search: id:A102011
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| A102011 |
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Indices of primes in sequence defined by A(0) = 19, A(n) = 10*A(n-1) - 61 for n > 0. |
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+0
2
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OFFSET
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1,2
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COMMENT
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Numbers n such that (110*10^n + 61)/9 is prime.
Numbers n such that digit 1 followed by n >= 0 occurrences of digit 2 followed by digit 9 is prime.
Numbers corresponding to terms <= 546 are certified primes.
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REFERENCES
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Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
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EXAMPLE
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1222229 is prime, hence 5 is a term.
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PROGRAM
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(PARI) a=19; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-61)
(PARI) for(n=0, 1500, if(isprime((110*10^n+61)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A102931(n) - 1.
Sequence in context: A112266 A060808 A099658 this_sequence A004098 A005114 A081090
Adjacent sequences: A102008 A102009 A102010 this_sequence A102012 A102013 A102014
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KEYWORD
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nonn,hard,more
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AUTHOR
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Klaus Brockhaus (klaus-brockhaus(AT)t-online.de) and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 28 2004
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