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 A262937 #60 Jun 09 2024 18:06:02 %S A262937 0,1,2,4,5,8,10,14,17,20,33,64,80,152,158,166,194,196,198,901,971, %T A262937 1289,1595,2921,14390,28781,35840 %N A262937 Numbers k such that (28*10^k - 13) / 3 is prime. %C A262937 For k > 1, numbers k such that the digit 9 followed by k-2 occurrences of the digit 3 followed by the digits 29 is prime (see Example section). %C A262937 a(28) > 3*10^5. %H A262937 Makoto Kamada, <a href="https://stdkmd.net/nrr">Factorization of near-repdigit-related numbers</a>. %H A262937 Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/prime_difficulty.txt">Search for 93w29</a>. %e A262937 2 is in this sequence because (28*10^2 - 13) / 3 = 929 is prime. %e A262937 Initial terms and associated primes: %e A262937 a(1) = 0, 5; %e A262937 a(2) = 1, 89; %e A262937 a(3) = 2, 929; %e A262937 a(4) = 4, 93329; %e A262937 a(5) = 5, 933329, etc. %t A262937 Select[Range[0, 100000], PrimeQ[(28*10^# - 13) / 3] &] %o A262937 (PARI) is(n)=ispseudoprime((28*10^n - 13)/3) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A262937 Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269. %K A262937 nonn,more %O A262937 1,3 %A A262937 _Robert Price_, Sep 23 2016