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A101526
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Indices of primes in sequence defined by A(0) = 67, A(n) = 10*A(n-1) - 33 for n > 0.
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0
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0, 2, 3, 4, 5, 9, 12, 57, 95, 177, 359, 419, 454, 1007, 1516, 2974, 3998, 5424
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OFFSET
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1,2
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COMMENTS
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Numbers n such that (570*10^n + 33)/9 is prime.
Numbers n such that digit 6 followed by n >= 0 occurrences of digit 3 followed by digit 7 is prime.
Numbers corresponding to terms <= 454 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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LINKS
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Table of n, a(n) for n=1..18.
Makoto Kamada, Factorizations of near-repdigit numbers.
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EXAMPLE
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633337 is prime, hence 4 is a term.
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PROG
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(PARI) a=67; for(n=0, 1200, if(isprime(a), print1(n, ", ")); a=10*a-33)
(PARI) for(n=0, 1200, if(isprime((570*10^n+33)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A103033(n) - 1.
Sequence in context: A038201 A033084 A076134 * A140298 A107365 A026484
Adjacent sequences: A101523 A101524 A101525 * A101527 A101528 A101529
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KEYWORD
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nonn,hard,more
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AUTHOR
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Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 06 2004
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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
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STATUS
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approved
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