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 A257123 #15 May 02 2015 10:20:04 %S A257123 275,2574,2725,2765,4762,5725,6762,7244,7262,23765,25744,27244,27325, %T A257123 27434,27465,27525,27632,27665,47725,52275,52376,52475,52576,52675, %U A257123 57242,67426,72266,72275,72424,72426,72576,72624,73325,73725,74326,75725,233725,233744 %N A257123 Numbers n such that the decimal expansions of both n and n^2 have 2 as smallest digit and 7 as largest digit. %H A257123 Felix Fröhlich, <a href="/A257123/b257123.txt">Table of n, a(n) for n = 1..1000</a> %o A257123 (PARI) is(n) = vecmin(digits(n))==2 && vecmin(digits(n^2))==2 && vecmax(digits(n))==7 && vecmax(digits(n^2))==7 %Y A257123 Cf. A137094, A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197, A257210, A257211, A256601, A257310, A249915, A257368, A257485, A257486, A257498, A257534. %K A257123 nonn,base %O A257123 1,1 %A A257123 _Felix Fröhlich_, Apr 25 2015