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Search: id:A101958
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| A101958 |
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Indices of primes in sequence defined by A(0) = 23, A(n) = 10*A(n-1) + 13 for n > 0. |
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+0
1
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| 0, 3, 6, 11, 29, 93, 177, 195, 563, 1800, 3519, 3537, 8232
(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 (220*10^n - 13)/9 is prime.
Numbers n such that digit 2 followed by n >= 0 occurrences of digit 4 followed by digit 3 is prime.
Numbers corresponding to terms <= 563 are certified primes.
With changed signs, expansion of sinh(atan(x)).
Next term after 3537 is greater than 5000. - Ryan Propper (rpropper(AT)stanford.edu), Jun 16 2005
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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 244...443.
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EXAMPLE
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24443 is prime, hence 3 is a term.
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PROGRAM
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(PARI) a=23; for(n=0, 2000, if(isprime(a), print1(n, ", ")); a=10*a+13)
(PARI) for(n=0, 2000, if(isprime((220*10^n-13)/9), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A102953(n) - 1.
Sequence in context: A001867 A000998 A109781 this_sequence A153982 A119367 A079801
Adjacent sequences: A101955 A101956 A101957 this_sequence A101959 A101960 A101961
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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 23 2004
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EXTENSIONS
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2 more terms from Ryan Propper (rpropper(AT)stanford.edu), Jun 16 2005
8232 from Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 28 2007
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