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A100999 Indices of primes in sequence defined by A(0) = 97, A(n) = 10*A(n-1) - 53 for n > 0. 1
0, 16, 22, 72, 130, 472, 684, 700, 1908, 3028, 3472, 4192, 9930 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Numbers n such that (820*10^n + 53)/9 is prime.
Numbers n such that digit 9 followed by n >= 0 occurrences of digit 1 followed by digit 7 is prime.
Numbers corresponding to terms <= 700 are certified primes.
a(14) > 10^5. - Robert Price, Oct 25 2015
REFERENCES
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
LINKS
FORMULA
a(n) = A100473(n) - 1.
EXAMPLE
911111111111111117 is prime, hence 16 is a term.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(820*10^# + 53)/9] &] (* Robert Price, Oct 25 2015 *)
PROG
(PARI) a=97; for(n=0, 1000, if(isprime(a), print1(n, ", ")); a=10*a-53)
(PARI) for(n=0, 1000, if(isprime((820*10^n+53)/9), print1(n, ", ")))
CROSSREFS
Sequence in context: A305337 A322344 A316417 * A304923 A306163 A317380
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
STATUS
approved

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Last modified July 21 09:16 EDT 2024. Contains 374472 sequences. (Running on oeis4.)