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A101062
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Indices of primes in sequence defined by A(0) = 83, A(n) = 10*A(n-1) - 7 for n > 0.
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0
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0, 1, 3, 4, 7, 9, 21, 222, 253, 349, 378, 400, 435, 1153, 1245, 2052, 2686, 3724, 4270
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Numbers n such that (740*10^n + 7)/9 is prime.
Numbers n such that digit 8 followed by n >= 0 occurrences of digit 2 followed by digit 3 is prime.
Numbers corresponding to terms <= 435 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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FORMULA
| a(n) = A103075(n) - 1. - Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
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EXAMPLE
| 822223is prime, hence 4 is a term.
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PROG
| (PARI) a=83; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-7)
(PARI) for(n=0, 1500, if(isprime((740*10^n+7)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
Sequence in context: A048849 A076211 A167186 * A003669 A047342 A137294
Adjacent sequences: A101059 A101060 A101061 * A101063 A101064 A101065
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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), Nov 30 2004
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EXTENSIONS
| More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
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