A101136 Indices of primes in sequence defined by A(0) = 79, A(n) = 10*A(n-1) - 61 for n > 0.
0, 2, 3, 6, 8, 12, 32, 36, 75, 146, 296, 1850, 3456, 3608, 45218
Offset: 1
Examples
72222229 is prime, hence 6 is a term.
References
- Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.
Links
Programs
-
Magma
[n: n in [0..3*10^2]| IsPrime((650*10^n+61) div 9)]; // Vincenzo Librandi, Oct 02 2015
-
Maple
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
-
Mathematica
Select[Range[0, 100000], PrimeQ[(650*10^# + 61)/9] &] (* Robert Price, Oct 01 2015 *)
-
PARI
a=79;for(n=0,1000,if(isprime(a),print1(n,","));a=10*a-61)
-
PARI
for(n=0,1000,if(isprime((650*10^n+61)/9),print1(n,",")))
Formula
a(n) = A103054(n) - 1.
Extensions
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
a(15) from Erik Branger May 01 2013 by Ray Chandler, Apr 30 2015
Comments