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Search: id:A101844
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| A101844 |
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Indices of primes in sequence defined by A(0) = 31, A(n) = 10*A(n-1) + 71 for n > 0. |
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+0
1
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| 0, 2, 18, 29, 39, 41, 44, 69, 306, 537, 1608, 1667, 1673, 4491, 4934, 6111
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Numbers n such that (350*10^n - 71)/9 is prime.
Numbers n such that digit 3 followed by n >= 0 occurrences of digit 8 followed by digit 1 is prime.
Numbers corresponding to terms <= 537 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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Makoto Kamada, Factorizations of near-repdigit numbers.
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EXAMPLE
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3881 is prime, hence 2 is a term.
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PROGRAM
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(PARI) a=31; for(n=0, 1700, if(isprime(a), print1(n, ", ")); a=10*a+71)
(PARI) for(n=0, 1700, if(isprime((350*10^n-71)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A102978(n) - 1.
Sequence in context: A115042 A098561 A141426 this_sequence A073213 A086490 A085876
Adjacent sequences: A101841 A101842 A101843 this_sequence A101845 A101846 A101847
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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 20 2004
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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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