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 A273726 #22 May 02 2024 04:24:47 %S A273726 1,2,3,5,7,26,52,75,97,98,160,227,295,413,686,901,975,1088,1481,2555, %T A273726 4001,4361,5637,7568,8641,19526,26633,92186 %N A273726 Numbers k such that (25*10^k + 59)/3 is prime. %C A273726 For k > 1, numbers k such that the digit 8 followed by k-2 occurrences of the digit 3 followed by the digits 53 is prime (see Example section). %C A273726 a(29) > 2*10^5. %H A273726 Makoto Kamada, <a href="https://stdkmd.net/nrr">Factorization of near-repdigit-related numbers</a>. %H A273726 Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/prime_difficulty.txt">Search for 83w53</a>. %e A273726 3 is in this sequence because (25*10^3+59)/3 = 8353 is prime. %e A273726 Initial terms and associated primes: %e A273726 a(1) = 1, 103; %e A273726 a(2) = 2, 853; %e A273726 a(3) = 3, 8353; %e A273726 a(4) = 5, 833353; %e A273726 a(5) = 6, 83333353, etc. %t A273726 Select[Range[0, 100000], PrimeQ[(25*10^# + 59)/3] &] %o A273726 (PARI) is(n)=ispseudoprime((25*10^n + 59)/3) \\ _Charles R Greathouse IV_, Jun 08 2016 %Y A273726 Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269. %K A273726 nonn,more %O A273726 1,2 %A A273726 _Robert Price_, May 28 2016