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 A257310 #22 Sep 10 2017 11:19:16
%S A257310 235,2335,23335,233335,2333335,2354235,23333335,233333335,2333333335,
%T A257310 2333524235,23333333335,23333524235,233333333335,2333333333335,
%U A257310 23333333333335,233333333333335,2333333333333335,23333333333333335,233333333333333335,2333333333333333335
%N A257310 Numbers n such that the decimal expansions of both n and n^2 have 2 as smallest digit and 5 as largest digit.
%C A257310 Conjecture: a(n) = A137066(n+2) for all n, i.e., this is A137066 without the initial two terms.
%C A257310 (10^(k+1)-1)/3 - 10^k + 2 are terms for k > 1. Conjecture: except for 2354235, 2333524235, and 23333524235, all terms are of this form. - _Chai Wah Wu_, Sep 10 2017
%H A257310 Chai Wah Wu, <a href="/A257310/b257310.txt">Table of n, a(n) for n = 1..40</a> (n = 1..31 from Hiroaki Yamanouchi)
%t A257310 fQ[n_] := Block[{d = DigitCount@ n}, Plus @@ Prepend[Take[d, {6, 10}], First@ d] == 0 && d[[2]] > 0 && d[[5]] > 0]; Select[Range@ 1000000, fQ@ # && fQ[#^2] &] (* _Michael De Vlieger_, Apr 20 2015 *)
%o A257310 (PARI) is(n) = vecmin(digits(n))==2 && vecmin(digits(n^2))==2 && vecmax(digits(n))==5 && vecmax(digits(n^2))==5
%Y A257310 Cf. A137066, A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197, A257210, A257211.
%K A257310 nonn,base
%O A257310 1,1
%A A257310 _Felix Fröhlich_, Apr 20 2015
%E A257310 a(11)-a(20) from _Hiroaki Yamanouchi_, May 04 2015