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 A102030 Indices of primes in sequence defined by A(0) = 13, A(n) = 10*A(n-1) + 53 for n > 0. 1
 0, 15, 21, 27, 33, 89, 2067, 2373, 2853, 3719, 4241, 22665, 29291, 29507 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Numbers n such that (170*10^n - 53)/9 is prime. Numbers n such that digit 1 followed by n >= 0 occurrences of digit 8 followed by digit 3 is prime. Numbers corresponding to terms <= 89 are certified primes. a(15) > 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 188...883. FORMULA a(n) = A102944(n) - 1. EXAMPLE 13 is prime, hence 0 is a term. PROG (PARI) a=13; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+53) (PARI) for(n=0, 1500, if(isprime((170*10^n-53)/9), print1(n, ", "))) CROSSREFS Cf. A000533, A002275, A102944. Sequence in context: A072974 A226025 A082686 * A168104 A026048 A195527 Adjacent sequences: A102027 A102028 A102029 * A102031 A102032 A102033 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(12)-a(14) derived from A102944 by Robert Price, Feb 11 2015 STATUS approved

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Last modified March 31 04:34 EDT 2023. Contains 361627 sequences. (Running on oeis4.)