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A101015 Indices of primes in sequence defined by A(0) = 93, A(n) = 10*A(n-1) + 43 for n > 0. 1
5, 14, 35, 44, 446, 1030, 1238, 3491, 6068, 13646, 17237, 56270, 72710, 75380 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Numbers n such that (880*10^n - 43)/9 is prime.
Numbers n such that digit 9 followed by n >= 0 occurrences of digit 7 followed by digit 3 is prime.
Numbers corresponding to terms <= 1030 are certified primes.
a(15) > 10^5. - Robert Price, Nov 12 2015
REFERENCES
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
LINKS
FORMULA
a(n) = A103106(n+1) - 1.
EXAMPLE
9777773 is prime, hence 5 is a term.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(880*10^# - 43)/9] &] (* Robert Price, Nov 12 2015 *)
PROG
(PARI) a=93; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+43)
(PARI) for(n=0, 1500, if(isprime((880*10^n-43)/9), print1(n, ", ")))
CROSSREFS
Sequence in context: A047860 A369887 A083332 * A076858 A001215 A335651
KEYWORD
nonn,hard,more
AUTHOR
Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Nov 27 2004
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
a(10)-a(11) from Kamada data by Ray Chandler, Apr 29 2015
a(12)-a(14) from Robert Price, Nov 12 2015
STATUS
approved

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Last modified April 18 22:18 EDT 2024. Contains 371782 sequences. (Running on oeis4.)