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Search: id:A101571
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| A101571 |
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Indices of primes in sequence defined by A(0) = 57, A(n) = 10*A(n-1) - 53 for n > 0. |
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1
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OFFSET
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1,1
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COMMENT
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Numbers n such that (460*10^n + 53)/9 is prime.
Numbers n such that digit 5 followed by n >= 0 occurrences of digit 1 followed by digit 7 is prime.
Numbers corresponding to terms <= 52 are certified primes. No further terms up to 2400.
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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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511111111111111111111117 is prime, hence 22 is a term.
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PROGRAM
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(PARI) a=57; for(n=0, 1000, if(isprime(a), print1(n, ", ")); a=10*a-53)
(PARI) for(n=0, 1000, if(isprime((460*10^n+53)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A103006(n) - 1.
Sequence in context: A015226 A092221 A111576 this_sequence A122502 A063302 A088820
Adjacent sequences: A101568 A101569 A101570 this_sequence A101572 A101573 A101574
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KEYWORD
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nonn,bref,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 09 2004
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