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 A112321 #12 Apr 28 2019 18:05:52 %S A112321 2,17,157,1547,15094,203879,0,0,0 %N A112321 Least n-digit number whose square is exclusionary, or 0 if no such number exists. %C A112321 m has an exclusionary square if m consists of distinct digits and m^2 is made up only of digits not appearing in m. %C A112321 a(10) = 0 since 10-digit numbers either use all digits or at least one digit more than once; a(n) = 0 for n > 10 since numbers with more than 10 digits use at least one digit more than once. %D A112321 H. Ibstedt, Solution to Problem 2623 "Exclusionary Powers", Journal of Recreational Mathematics pp. 346-9 Vol. 32 no. 4 2003-4 Baywood NY. %Y A112321 Cf. A112322 (corresponding squares), A110815. %K A112321 nonn,base,fini %O A112321 1,1 %A A112321 _Lekraj Beedassy_ and _Klaus Brockhaus_, Sep 08 2005