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 A102027 Indices of primes in sequence defined by A(0) = 13, A(n) = 10*A(n-1) + 43 for n > 0. 1
 0, 1, 7, 25, 43, 166, 184, 3817, 8740, 50794 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Numbers n such that (160*10^n - 43)/9 is prime. Numbers n such that digit 1 followed by n >= 0 occurrences of digit 7 followed by digit 3 is prime. Numbers corresponding to terms <= 184 are certified primes. a(11) > 10^5. - Robert Price, Feb 11 2015 REFERENCES Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467. LINKS Makoto Kamada, Prime numbers of the form 177...773. FORMULA a(n) = A102942(n) - 1. EXAMPLE 173 is prime, hence 1 is a term. PROG (PARI) a=13; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+43) (PARI) for(n=0, 1500, if(isprime((160*10^n-43)/9), print1(n, ", "))) CROSSREFS Cf. A000533, A002275, A102942. Sequence in context: A294459 A075927 A119617 * A031294 A147129 A173825 Adjacent sequences: A102024 A102025 A102026 * A102028 A102029 A102030 KEYWORD nonn,hard,more AUTHOR Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 28 2004 EXTENSIONS More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008 a(10) from Robert Price, Feb 11 2015 STATUS approved

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Last modified March 28 17:47 EDT 2023. Contains 361596 sequences. (Running on oeis4.)