%I #7 May 24 2019 16:40:22
%S 0,97,49,95,81,99,64,88,36,80,0,96,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
%T 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
%N a(n) = the largest 2-digit number with exactly n divisors, a(n) = 0 if no such number exists.
%F A000005(a(n)) = n for a(n) > 0.
%F 12 = max n such that a(n) > 0, a(n) = 0 for n > 12.
%t With[{ds=Reverse[Table[{n,DivisorSigma[0,n]},{n,10,99}]]},Table[ SelectFirst[ ds,#[[2]]==k&],{k,50}]][[All,1]]/."NotFound"->0 (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, May 24 2019 *)
%Y Cf. A182689.
%K nonn,base,less
%O 1,2
%A _Jaroslav Krizek_, Nov 27 2010