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 A237203 #6 Feb 05 2014 02:57:46
%S A237203 0,0,1,0,0,1,2,0,1,2,1,2,1,2,5,7,5,1,2,4,6,3,3,4,6,6,3,4,12,3,4,14,1,
%T A237203 2,1,2,5,1,2,8,1,2,16,6,5,7,10,8,1,2,17,7,5,3,4,8,3,1,2,6,1,2,7,1,2,
%U A237203 11,3,4,12,6
%N A237203 Least positive integer k < n/2 with phi(k)*phi(n-k) a square, or 0 if such a number k does not exist.
%C A237203 Conjecture: a(n) < sqrt(n)*log(2*n) for all n > 0.
%C A237203 We have verified this for n up to 2*10^5. Note that a(211) = 85 > sqrt(211)*log(211) and a(373) = 117 > sqrt(373)*log(373).
%C A237203 According to the conjecture in A236998, a(n) should be positive for all n > 8.
%H A237203 Zhi-Wei Sun, <a href="/A237203/b237203.txt">Table of n, a(n) for n = 1..10000</a>
%e A237203 a(7) = 2 since phi(2)*phi(7-2) = 1*4 = 2^2 but phi(1)*phi(7-1) = 2 is not a square.
%t A237203 SQ[k_,m_]:=IntegerQ[Sqrt[EulerPhi[k]*EulerPhi[m]]]
%t A237203 Do[Do[If[SQ[k,n-k],Print[n," ",k];Goto[aa]],{k,1,(n-1)/2}];
%t A237203 Print[n," ",0];Label[aa];Continue,{n,1,70}]
%Y A237203 Cf. A000010, A000290, A236998.
%K A237203 nonn
%O A237203 1,7
%A A237203 _Zhi-Wei Sun_, Feb 05 2014