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A101849
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Indices of primes in sequence defined by A(0) = 37, A(n) = 10*A(n-1) + 27 for n > 0.
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2
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OFFSET
| 1,3
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COMMENTS
| Numbers n such that (360*10^n - 27)/9 is prime.
Numbers n such that digit 3 followed by n >= 0 occurrences of digit 9 followed by digit 7 is prime.
Numbers corresponding to terms <= 871 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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LINKS
| Makoto Kamada, Factorizations of near-repdigit numbers.
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EXAMPLE
| 397 is prime, hence 1 is a term.
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PROG
| (PARI) a=37; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+27)
(PARI) for(n=0, 1500, if(isprime((360*10^n-27)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275, A101155, A169830.
a(n) = A101398(n) - 1.
Sequence in context: A038954 A005106 A120140 * A141562 A108097 A102764
Adjacent sequences: A101846 A101847 A101848 * A101850 A101851 A101852
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KEYWORD
| nonn,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 20 2004
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EXTENSIONS
| 8845 from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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