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A101955 Indices of primes in sequence defined by A(0) = 29, A(n) = 10*A(n-1) - 71 for n > 0. 1
0, 222, 317, 426, 3726, 5226, 8778, 11382, 15414, 26381 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Numbers n such that (190*10^n + 71)/9 is prime.
Numbers n such that digit 2 followed by n >= 0 occurrences of digit 1 followed by digit 9 is prime.
Numbers corresponding to terms <= 426 are certified primes.
a(11) > 10^5. - Robert Price, Feb 06 2015
REFERENCES
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
LINKS
FORMULA
a(n) = A102950(n) - 1.
EXAMPLE
29 is prime, hence 0 is a term.
PROG
(PARI) a=29; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a-71)
(PARI) for(n=0, 1500, if(isprime((190*10^n+71)/9), print1(n, ", ")))
CROSSREFS
Sequence in context: A345521 A345775 A361628 * A063352 A250521 A043499
KEYWORD
nonn,hard,more
AUTHOR
Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 23 2004
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
a(8)-a(10) derived from A102950 by Robert Price, Feb 06 2015
STATUS
approved

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Last modified July 14 20:49 EDT 2024. Contains 374323 sequences. (Running on oeis4.)