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A101143
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Indices of primes in sequence defined by A(0) = 71, A(n) = 10*A(n-1) + 41 for n > 0.
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0
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0, 1, 4, 6, 22, 31, 37, 46, 115, 139, 228, 246, 733, 930, 1345, 2161, 2545, 6979
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Numbers n such that (680*10^n - 41)/9 is prime.
Numbers n such that digit 7 followed by n >= 0 occurrences of digit 5 followed by digit 1 is prime.
Numbers corresponding to terms <= 930 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
| 751 is prime, hence 1 is a term.
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PROG
| (PARI) a=71; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+41)
(PARI) for(n=0, 1500, if(isprime((680*10^n-41)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
a(n) = A103060(n) - 1.
Sequence in context: A002270 A088228 A108636 * A083157 A192154 A151519
Adjacent sequences: A101140 A101141 A101142 * A101144 A101145 A101146
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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 03 2004
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EXTENSIONS
| More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
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