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A101129
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Indices of primes in sequence defined by A(0) = 73, A(n) = 10*A(n-1) - 27 for n > 0.
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0
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0, 3, 5, 15, 21, 38, 102, 162, 239, 1047, 1973, 2558, 5879
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Numbers n such that 70*10^n + 3 is prime.
Numbers n such that digit 7 followed by n >= 0 occurrences of digit 0 followed by digit 3 is prime.
Numbers corresponding to terms <= 239 are certified primes.
Certified primality of number corresponding to term 1047 with Primo. - Ryan Propper (rpropper(AT)stanford.edu), Jun 20 2005
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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
| 7000003 is prime, hence 5 is a term.
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PROG
| (PARI) a=73; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-27)
(PARI) for(n=0, 1500, if(isprime(70*10^n+3), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
a(n) = A097970(n) - 1.
Sequence in context: A142717 A057742 A201433 * A177916 A128396 A155173
Adjacent sequences: A101126 A101127 A101128 * A101130 A101131 A101132
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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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