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 A101589 Indices of primes in sequence defined by A(0) = 59, A(n) = 10*A(n-1) - 1 for n > 0. 1
 0, 3, 7, 12, 15, 43, 438, 607, 1200, 2724, 5209, 59388, 118215, 198528 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Numbers n such that (530*10^n + 1)/9 is prime. Numbers n such that digit 5 followed by n >= 0 occurrences of digit 8 followed by digit 9 is prime. Numbers corresponding to terms <= 607 are certified primes. 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 588...889. FORMULA a(n) = A103024(n) - 1. EXAMPLE 58889 is prime, hence 3 is a term. PROG (PARI) a=59; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-1) (PARI) for(n=0, 1500, if(isprime((530*10^n+1)/9), print1(n, ", "))) CROSSREFS Cf. A000533, A002275, A103024. Sequence in context: A331042 A122981 A122982 * A061559 A165990 A160998 Adjacent sequences:  A101586 A101587 A101588 * A101590 A101591 A101592 KEYWORD nonn,more AUTHOR Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 09 2004 EXTENSIONS More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008 a(12)-a(14) from Kamada data by Ray Chandler, Apr 30 2015 STATUS approved

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Last modified May 17 21:11 EDT 2021. Contains 343990 sequences. (Running on oeis4.)