This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A102011 #22 Feb 01 2023 21:54:09 %S A102011 0,2,5,50,56,62,149,392,419,546,42023,43062,101612,107384 %N A102011 Indices of primes in sequence defined by A(0) = 19, A(n) = 10*A(n-1) - 61 for n > 0. %C A102011 Numbers n such that (110*10^n + 61)/9 is prime. %C A102011 Numbers n such that digit 1 followed by n >= 0 occurrences of digit 2 followed by digit 9 is prime. %C A102011 Numbers corresponding to terms <= 546 are certified primes. %C A102011 a(13) > 10^5. - _Robert Price_, Jan 17 2015 %C A102011 a(15) > 2*10^5. - _Tyler Busby_, Feb 01 2023 %D A102011 Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467. %H A102011 Makoto Kamada, <a href="https://stdkmd.net/nrr/1/12229.htm#prime">Prime numbers of the form 122...229</a>. %H A102011 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>. %F A102011 a(n) = A102931(n) - 1. %e A102011 1222229 is prime, hence 5 is a term. %o A102011 (PARI) a=19;for(n=0,1500,if(isprime(a),print1(n,","));a=10*a-61) %o A102011 (PARI) for(n=0,1500,if(isprime((110*10^n+61)/9),print1(n,","))) %Y A102011 Cf. A000533, A002275, A102931. %K A102011 nonn,hard,more %O A102011 1,2 %A A102011 _Klaus Brockhaus_ and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 28 2004 %E A102011 a(11)-a(12) derived from A102931 by _Robert Price_, Jan 17 2015 %E A102011 a(13)-a(14) from _Tyler Busby_, Jan 31 2023