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A101960
Indices of primes in sequence defined by A(0) = 29, A(n) = 10*A(n-1) - 41 for n > 0.
1
0, 14, 30, 72, 96, 498, 4206, 5901, 9567, 12141, 13047, 38340, 80166, 91902
OFFSET
1,2
COMMENTS
Numbers n such that (220*10^n + 41)/9 is prime.
Numbers n such that digit 2 followed by n >= 0 occurrences of digit 4 followed by digit 9 is prime.
Numbers corresponding to terms <= 498 are certified primes.
a(15) > 10^5. - Robert Price, Feb 05 2015
REFERENCES
Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
FORMULA
a(n) = A102955(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-41)
(PARI) for(n=0, 1500, if(isprime((220*10^n+41)/9), print1(n, ", ")))
CROSSREFS
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(10)-a(14) from Robert Price, Feb 05 2015
STATUS
approved