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 A256601 #21 Apr 20 2015 21:07:28
%S A256601 139,219,519,591,719,891,911,961,971,981,1139,1193,1219,1292,1293,
%T A256601 1296,1319,1339,1389,1391,1392,1394,1396,1469,1579,1589,1691,1719,
%U A256601 1729,1769,1793,1839,1869,1896,1911,1927,1937,1939,1944,1946,1969,1978,1979,1981,1986
%N A256601 Numbers n such that the decimal expansions of both n and n^2 have 1 as smallest digit and 9 as largest digit.
%H A256601 Felix Fröhlich, <a href="/A256601/b256601.txt">Table of n, a(n) for n = 1..10000</a>
%t A256601 fQ[n_] := Block[{d = DigitCount@ n}, Last@ d == 0 && d[[1]] > 0 && d[[9]] > 0]; Select[Range@ 2000, fQ@ # && fQ[#^2] &] (* _Michael De Vlieger_, Apr 20 2015 *)
%o A256601 (PARI) is(n) = vecmin(digits(n))==1 && vecmin(digits(n^2))==1 && vecmax(digits(n))==9 && vecmax(digits(n^2))==9
%Y A256601 Cf. A256630, A256631, A256633, A256634, A256708, A256709, A256889, A257197, A257210, A257211.
%K A256601 nonn,base
%O A256601 1,1
%A A256601 _Felix Fröhlich_, Apr 20 2015