A101577 - OEIS

%I #15 Jan 17 2019 13:44:06

%S 0,46,68,98,574,714,2178,10540

%N Indices of primes in sequence defined by A(0) = 59, A(n) = 10*A(n-1) - 51 for n > 0.

%C Numbers n such that (480*10^n + 51)/9 is prime.

%C Numbers n such that digit 5 followed by n >= 0 occurrences of digit 3 followed by digit 1 is prime.

%C Numbers corresponding to terms <= 714 are certified primes.

%C a(9) > 10^5. - _Robert Price_, Sep 08 2015

%D Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.

%H Makoto Kamada, <a href="https://stdkmd.net/nrr/5/53339.htm#prime">Prime numbers of the form 533...339</a>.

%H <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.

%F a(n) = A103012(n+1) - 1.

%e 59 is prime, hence 0 is a term.

%t Select[Range[0, 10000], PrimeQ[(480*10^# + 51)/9] &] (* _Robert Price_, Sep 08 2015 *)

%o (PARI) a=59;for(n=0,1000,if(isprime(a),print1(n,","));a=10*a-51)

%o (PARI) for(n=0,1000,if(isprime((480*10^n+51)/9),print1(n,",")))

%Y Cf. A000533, A002275, A103012.

%K nonn,more

%O 1,2

%A _Klaus Brockhaus_ and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 09 2004

%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008

%E a(8) from Kamada data by _Ray Chandler_, Apr 30 2015