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A102027
Indices of primes in sequence defined by A(0) = 13, A(n) = 10*A(n-1) + 43 for n > 0.
1
0, 1, 7, 25, 43, 166, 184, 3817, 8740, 50794
OFFSET
1,3
COMMENTS
Numbers n such that (160*10^n - 43)/9 is prime.
Numbers n such that digit 1 followed by n >= 0 occurrences of digit 7 followed by digit 3 is prime.
Numbers corresponding to terms <= 184 are certified primes.
a(11) > 10^5. - Robert Price, Feb 11 2015
REFERENCES
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
FORMULA
a(n) = A102942(n) - 1.
EXAMPLE
173 is prime, hence 1 is a term.
PROG
(PARI) a=13; for(n=0, 1500, if(isprime(a), print1(n, ", ")); a=10*a+43)
(PARI) for(n=0, 1500, if(isprime((160*10^n-43)/9), print1(n, ", ")))
CROSSREFS
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(10) from Robert Price, Feb 11 2015
STATUS
approved