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 A379603 #29 Jan 11 2025 19:18:37
%S A379603 3,83,937,9833,98336,998333,9994833,99983333,999939437,9999833333,
%T A379603 99998333336,999998333333,9999983333336,99999983333333,
%U A379603 999999833333336,9999999833333333,99999998333333336,999999998333333333,9999999983333333336,99999999983333333333,999999999833333333336
%N A379603 a(n) is the largest n-digit number whose square contains only digits greater than 5.
%F A379603 Conjecture: It appears that for all n >= 5,
%F A379603 a(2*n) = 100^n - (5*10^n + 1)/3, and
%F A379603 a(2*n + 1) = 10*a(2*n) + 6.
%e A379603 a(3) = 937 because among all 3-digit numbers, 937 is the largest whose square 877969 contains only digits greater than 5.
%t A379603 f[m_] := For[k = 10^m - 1, k > 10^(m - 1), k--, If[Min@IntegerDigits[k^2] > 5, Return[k];]];
%t A379603 Table[f[m], {m, 10}]
%Y A379603 Cf. A053972, A053974, A058471, A164778, A164772, A164773, A164841, A291631, A379602.
%K A379603 nonn,base
%O A379603 1,1
%A A379603 _Zhining Yang_, Dec 27 2024
%E A379603 a(20)-a(21) from _Jinyuan Wang_, Dec 27 2024