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Search: id:A101518
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| A101518 |
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Indices of primes in sequence defined by A(0) = 67, A(n) = 10*A(n-1) - 63 for n > 0. |
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+0
1
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| 0, 1, 2, 7, 8, 18, 57, 120, 186, 805, 854, 1018, 2592, 2748, 3015, 4294, 9663
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Numbers n such that 60*10^n + 7 is prime.
Numbers n such that digit 6 followed by n >= 0 occurrences of digit 0 followed by digit 7 is prime.
Numbers corresponding to terms <= 854 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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6007 is prime, hence 2 is a term.
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MATHEMATICA
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For[n=1, n<=3000, n++, If[PrimeQ[60*10^n+7], Print[n]]] (Steinerberger)
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PROGRAM
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(PARI) a=67; for(n=0, 1200, if(isprime(a), print1(n, ", ")); a=10*a-63)
(PARI) for(n=0, 1200, if(isprime(60*10^n+7), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A103026(n) - 1.
Adjacent sequences: A101515 A101516 A101517 this_sequence A101519 A101520 A101521
Sequence in context: A023178 A080572 A032689 this_sequence A055247 A015617 A026579
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KEYWORD
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nonn,hard
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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 06 2004
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EXTENSIONS
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a(13)-a(15) from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Feb 03 2006
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
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