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A101136 Indices of primes in sequence defined by A(0) = 79, A(n) = 10*A(n-1) - 61 for n > 0.

%I A101136 #24 Sep 08 2022 08:45:16
%S A101136 0,2,3,6,8,12,32,36,75,146,296,1850,3456,3608,45218
%N A101136 Indices of primes in sequence defined by A(0) = 79, A(n) = 10*A(n-1) - 61 for n > 0.
%C A101136 Numbers n such that (650*10^n + 61)/9 is prime.
%C A101136 Numbers n such that digit 7 followed by n >= 0 occurrences of digit 2 followed by digit 9 is prime.
%C A101136 Numbers corresponding to terms <= 296 are certified primes.
%C A101136 a(16) > 10^5. - _Robert Price_, Oct 01 2015
%C A101136 All a(n) == 0, 2 or 3 mod 6 (cf. A047244). - _Robert Israel_, Oct 01 2015
%D A101136 Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
%H A101136 Makoto Kamada, <a href="https://stdkmd.net/nrr/7/72229.htm#prime">Prime numbers of the form 722...229</a>.
%H A101136 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.
%F A101136 a(n) = A103054(n) - 1.
%e A101136 72222229 is prime, hence 6 is a term.
%p A101136 select(t -> isprime((650*10^t + 61)/9), [seq(seq(6*s+i,i=[0,2,3]),s=0..700)]); # _Robert Israel_, Oct 01 2015
%t A101136 Select[Range[0, 100000], PrimeQ[(650*10^# + 61)/9] &] (* _Robert Price_, Oct 01 2015 *)
%o A101136 (PARI) a=79;for(n=0,1000,if(isprime(a),print1(n,","));a=10*a-61)
%o A101136 (PARI) for(n=0,1000,if(isprime((650*10^n+61)/9),print1(n,",")))
%o A101136 (Magma) [n: n in [0..3*10^2]| IsPrime((650*10^n+61) div 9)]; // _Vincenzo Librandi_, Oct 02 2015
%Y A101136 Cf. A000533, A002275, A103054.
%K A101136 nonn,hard,more
%O A101136 1,2
%A A101136 _Klaus Brockhaus_ and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 03 2004
%E A101136 More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
%E A101136 a(15) from Erik Branger May 01 2013 by _Ray Chandler_, Apr 30 2015