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A102033
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Indices of primes in sequence defined by A(0) = 13, A(n) = 10*A(n-1) + 63 for n > 0.
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0
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0, 1, 2, 3, 5, 15, 20, 27, 47, 81, 121, 129, 281, 303, 4601, 12983, 13613
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Numbers n such that (180*10^n - 63)/9 is prime.
Numbers n such that digit 1 followed by n >= 0 occurrences of digit 9 followed by digit 3 is prime.
Numbers corresponding to terms <= 303 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
| 193 is prime, hence 1 is a term.
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PROG
| (PARI) a=13; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+63)
(PARI) for(n=0, 1500, if(isprime((180*10^n-63)/9), print1(n, ", ")))
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CROSSREFS
| Cf. A000533, A002275.
a(n) = A102946(n) - 1.
Sequence in context: A114411 A155698 A099410 * A174418 A072246 A024781
Adjacent sequences: A102030 A102031 A102032 * A102034 A102035 A102036
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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 28 2004
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EXTENSIONS
| More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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