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 A275473 #8 Jul 29 2016 08:41:44 %S A275473 1,4,3,9,8,12,8,10,12,18,8,20,8,18,24,8,8,0,8,24,24,18,8,16,9,18,0,20, %T A275473 8,0,8,14,24,18,36,24,8,18,24,16,8,40,8,20,0,18,8,24,9,36,24,20,8,18, %U A275473 36,16,24,18,8,32,8,18,0,0,36,40,8,20,24,48 %N A275473 Least k such that d(k*n) = k, or 0 if no such k exists (d = A000005). %e A275473 a(4) = 9 because A000005(9*4) = 9. %t A275473 up[t_] := If[t < 15, 18, t^(1.066/Log[Log[t]])]; a[n_] := Catch@ Block[{k = 1}, While[ up[k*n]/k > 1, If[ DivisorSigma[0, k n] == k, Throw@ k, k++]]; 0]; Array[a, 70] (* _Giovanni Resta_, Jul 29 2016 *) %Y A275473 Cf. A000005, A036763. %K A275473 nonn %O A275473 1,2 %A A275473 _Altug Alkan_, Jul 29 2016