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A101528 Indices of primes in sequence defined by A(0) = 63, A(n) = 10*A(n-1) + 13 for n > 0. 1
1, 4, 5, 10, 14, 68, 89, 133, 188, 244, 266, 269, 469, 1574, 2294, 2506, 3511, 3824, 6856, 11021, 11656, 17498, 35035, 41965, 50557, 93061 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Numbers n such that (580*10^n - 13)/9 is prime.
Numbers n such that digit 6 followed by n >= 0 occurrences of digit 4 followed by digit 3 is prime.
Numbers corresponding to terms <= 469 are certified primes.
a(27) > 10^5. - Robert Price, Sep 12 2015
REFERENCES
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
LINKS
FORMULA
a(n) = A103035(n+1) - 1.
EXAMPLE
6444443 is prime, hence 5 is a term.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(580*10^# - 13)/9] &] (* Robert Price, Sep 12 2015 *)
PROG
(PARI) a=63; for(n=0, 1000, if(isprime(a), print1(n, ", ")); a=10*a+13)
(PARI) for(n=0, 1000, if(isprime((580*10^n-13)/9), print1(n, ", ")))
CROSSREFS
Sequence in context: A116930 A073119 A002257 * A119040 A287578 A135104
KEYWORD
nonn,hard,more
AUTHOR
Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 06 2004
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
a(20)-a(24) from Kamada data by Ray Chandler, Apr 30 2015
a(25)-a(26) from Robert Price, Sep 12 2015
STATUS
approved

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Last modified March 28 21:56 EDT 2024. Contains 371254 sequences. (Running on oeis4.)