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 A248352 #21 Dec 05 2019 17:25:47 %S A248352 986,1240,1928,4054,14252,47528,101728 %N A248352 Numbers k such that 10^k - 987654321 is prime. %C A248352 Note that 987654321 is the largest pandigital number in base-10, omitting 0. %t A248352 Select[Range[10000], PrimeQ[10^# - 987654321] &] (* _Robert Price_, Dec 05 2019 *) %o A248352 (PARI) for(n=1,10^4,if(ispseudoprime(10^n-987654321),print1(n,", "))) %Y A248352 Cf. A248349, A248350, A248351, A050289. %K A248352 nonn,hard,more %O A248352 1,1 %A A248352 _Derek Orr_, Oct 05 2014 %E A248352 a(6)-a(7) from _Robert Price_, Dec 05 2019