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A101069
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Indices of primes in sequence defined by A(0) = 89, A(n) = 10*A(n-1) - 41 for n > 0.
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0
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OFFSET
| 1,2
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COMMENTS
| Numbers n such that (760*10^n + 41)/9 is prime.
Numbers n such that digit 8 followed by n >= 0 occurrences of digit 4 followed by digit 9 is prime.
Numbers corresponding to terms <= 468 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) = A103082(n) - 1. - Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
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EXAMPLE
| 84449 is prime, hence 3 is a term.
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MATHEMATICA
| Select[Range[0, 5700], PrimeQ[FromDigits[Join[PadRight[{8}, #+1, 4], {9}]]]&] (* From Harvey P. Dale, Jan 23 2012 *)
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PROG
| (PARI) a=89; for(n=0, 1000, if(isprime(a), print1(n, ", ")); a=10*a-41)
(PARI) for(n=0, 1000, if(isprime((760*10^n+41)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
Sequence in context: A097339 A009787 A135190 * A167667 A027327 A167993
Adjacent sequences: A101066 A101067 A101068 * A101070 A101071 A101072
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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
| One more term from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
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