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A101956
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Indices of primes in sequence defined by A(0) = 29, A(n) = 10*A(n-1) - 51 for n > 0.
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0
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0, 1, 2, 3, 7, 10, 12, 23, 27, 51, 53, 93, 296, 656, 1005, 5346, 8188, 9313
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Numbers n such that (210*10^n + 51)/9 is prime.
Numbers n such that digit 2 followed by n >= 0 occurrences of digit 3 followed by digit 9 is prime.
Numbers corresponding to terms <= 656 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
| 2339 is prime, hence 2 is a term.
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MATHEMATICA
| Transpose[Select[Partition[With[{no=10000}, Riffle[NestList[10#-51&, 29, no], Range[0, no]]], 2], PrimeQ[First[#]]&]][[2]] (* From Harvey P. Dale, Feb 05 2011 *)
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PROG
| (PARI) a=29; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-51)
(PARI) for(n=0, 1500, if(isprime((210*10^n+51)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
a(n) = A102951(n) - 1.
Sequence in context: A102808 A140512 A171863 * A002238 A002255 A192116
Adjacent sequences: A101953 A101954 A101955 * A101957 A101958 A101959
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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 23 2004
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EXTENSIONS
| More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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