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A102016
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Indices of primes in sequence defined by A(0) = 17, A(n) = 10*A(n-1) - 23 for n > 0.
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0
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0, 2, 3, 5, 8, 21, 27, 33, 36, 60, 81, 273, 275, 734, 1442, 2214, 2967, 3300, 3882, 3990, 5151, 8031, 8945
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Numbers n such that (130*10^n + 23)/9 is prime.
Numbers n such that digit 1 followed by n >= 0 occurrences of digit 4 followed by digit 7 is prime.
Numbers corresponding to terms <= 734 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
| 1447 is prime, hence 2 is a term.
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PROG
| (PARI) a=17; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-23)
(PARI) for(n=0, 1500, if(isprime((130*10^n+23)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
a(n) = A102934(n) - 1.
Sequence in context: A049908 A135568 A103004 * A002363 A041457 A161468
Adjacent sequences: A102013 A102014 A102015 * A102017 A102018 A102019
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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 28 2004
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EXTENSIONS
| More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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