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Search: id:A101712
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| A101712 |
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Indices of primes in sequence defined by A(0) = 41, A(n) = 10*A(n-1) - 9 for n > 0. |
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+0
1
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| 0, 1, 2, 12, 228, 241, 308, 956, 1472, 1493, 3181, 3726, 4176, 23209, 25718, 36989, 103957
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Numbers n such that 40*10^n + 1 is prime.
Numbers n such that digit 4 followed by n >= 0 occurrences of digit 0 followed by digit 1 is prime.
Numbers corresponding to terms <= 956 are certified primes.
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REFERENCES
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Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
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LINKS
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Makoto Kamada, Factorizations of near-repdigit numbers.
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EXAMPLE
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4001 is prime, hence 2 is a term.
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PROGRAM
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(PARI) a=41; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-9)
(PARI) for(n=0, 1500, if(isprime(40*10^n+1), print1(n, ", ")))
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CROSSREFS
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Cf. A000533, A002275.
a(n) = A056806(n) - 1.
Adjacent sequences: A101709 A101710 A101711 this_sequence A101713 A101714 A101715
Sequence in context: A009525 A009683 A132879 this_sequence A009272 A013141 A013143
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KEYWORD
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nonn,hard,more
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AUTHOR
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Klaus Brockhaus (klaus-brockhaus(AT)t-online.de) and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 14 2004
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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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