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 A039686 #33 Apr 26 2017 04:38:50
%S A039686 49,169,361,1225,1444,1681,3249,4225,4900,15625,16900,36100,42025,
%T A039686 49729,64009,81225,93025,122500,144400,168100,225625,237169,324900,
%U A039686 422500,490000,519841,819025,950625,970225,1024144,1442401,1562500
%N A039686 Squares which are the concatenation of two nonzero squares.
%C A039686 Intersection of A191933 and A000290; A193095(a(n))>0 and A010052(a(n))=1. - _Reinhard Zumkeller_, Jul 17 2011
%C A039686 Note that "leading zeros" are not allowed, e.g., 9025 = 95^2 is not in the sequence although it is the concatenation of 9 = 3^2 and 025 = 5^2. - _M. F. Hasler_, Jan 25 2016
%D A039686 D. Wells, Curious and interesting numbers, Penguin Books, p. 152.
%H A039686 Giovanni Resta, <a href="/A039686/b039686.txt">Table of n, a(n) for n = 1..3000</a> (first 1000 terms from David W. Wilson)
%F A039686 a(n) = A048375(n)^2. - _M. F. Hasler_, Jan 25 2016
%e A039686 1225=35^2, 225=15^2, 1=1^2.
%t A039686 t = Table[n^2, {n, 750}]; f[j_, k_] := Block[{n = j*10^Floor[1 + Log10@ k] + k}, If[IntegerQ@ Sqrt@ n, n, 0]]; Take[ Union@ Flatten@ Table[ f[t[[j]], t[[k]]], {j, 250}, {k, 750}], {2, 33}] (* _Robert G. Wilson v_, Jul 18 2011 *)
%t A039686 squareQ[n_] := IntegerQ[Sqrt[n]]; okQ[n_] := MatchQ[IntegerDigits[n], {a__ /; squareQ[FromDigits[{a}]], b__ /; First[{b}] > 0 && squareQ[FromDigits[ {b}]]}]; Select[Range[2000]^2, okQ] (* _Jean-François Alcover_, Dec 13 2016 *)
%o A039686 (Haskell)
%o A039686 a039686 n = a039686_list !! (n-1)
%o A039686 a039686_list = filter ((== 1) . a010052) a191933_list
%o A039686 -- _Reinhard Zumkeller_, Jul 17 2011
%o A039686 (PARI) is_A039686(n)={my(p=10);until(n<=p*=10,issquare(n%p)&&issquare(n\p)&&n%p*10>=p&&issquare(n)&&return(n>10))} \\ We must check whether n is a square but in practice this will be sure a priori (cf below) so we put this test at the end. The same applies for "n>10". - _M. F. Hasler_, Jan 25 2016
%o A039686 (PARI) {for(m=4,999, is_A039686(m^2)&&print1(m^2,","))} \\ Here the final checks issquare(n) & n>10 in the above function are superfluous, but they will only be done in the ("few") positive cases. - _M. F. Hasler_, Jan 25 2016
%Y A039686 Cf. A048375.
%K A039686 nonn,base
%O A039686 1,1
%A A039686 _Felice Russo_
%E A039686 More terms from _Patrick De Geest_, March 1999