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 A101964 #24 Jul 13 2023 12:25:43 %S A101964 0,1,2,4,5,6,10,20,29,67,72,168,175,344,822,1020,1190,2072,2754,10716, %T A101964 14672,16753,17605,81028,120850,167964,200407 %N A101964 Indices of primes in sequence defined by A(0) = 23, A(n) = 10*A(n-1) + 33 for n > 0. %C A101964 Numbers n such that (240*10^n - 33)/9 is prime. %C A101964 Numbers n such that digit 2 followed by n >= 0 occurrences of digit 6 followed by digit 3 is prime. %C A101964 Numbers corresponding to terms <= 822 are certified primes. %C A101964 a(28) > 3*10^5. - _Robert Price_, Jul 13 2023 %D A101964 Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467. %H A101964 Makoto Kamada, <a href="https://stdkmd.net/nrr/2/26663.htm#prime">Prime numbers of the form 266...663</a>. %H A101964 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>. %F A101964 a(n) = A098959(n) - 1. %e A101964 263 is prime, hence 1 is a term. %o A101964 (PARI) a=23;for(n=0,1500,if(isprime(a),print1(n,","));a=10*a+33) %o A101964 (PARI) for(n=0,1500,if(isprime((240*10^n-33)/9),print1(n,","))) %Y A101964 Cf. A000533, A002275, A098959. %K A101964 nonn,hard,more %O A101964 1,3 %A A101964 _Klaus Brockhaus_ and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 23 2004 %E A101964 More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008 %E A101964 a(24) derived from A098959 by _Robert Price_, Jan 17 2015 %E A101964 a(25)-a(27) derived from A098959 by _Robert Price_, Jul 13 2023