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 A131904 #7 Apr 03 2015 03:47:39
%S A131904 2,2,2,6,4,6,2,2,6,6,2,12,2,12,6,6,2,4,6,6,12,2,24,2,12,6,6,6,2,6,6,
%T A131904 24,2,24,2,12,12,6,2,4,12,6,12,2,24,6,24,6,6,2,2,6,12,6,24,2,12,6,24,
%U A131904 2,60,2,6,12,12,6,24,2,48,16,6,2,60,6,6,6,24,2
%N A131904 Smallest positive integer k with the same number of divisors as the n-th integer for which such a k exists.
%F A131904 a(n)=min(k>0, k has the same number of divisors as A131903(n))
%e A131904 a(4)=6 because A131903(4)=8, which has four divisors, and 6 is the least positive integer with four divisors
%t A131904 Clear[tmp]; Function[n, If[Head[ #1] === tmp, #1 = n; Unevaluated[Sequence[]], # ] & [tmp[DivisorSigma[0, n]]]] /@ Range[64]
%o A131904 (PARI) lista(nn) = {for (n=1, nn, my(nd = numdiv(n)); for (k=1, n-1, if (numdiv(k) == nd, print1(k, ", "); break);););} \\ _Michel Marcus_, Apr 03 2015
%Y A131904 Cf. A069822, A131902-A131908.
%K A131904 easy,nonn
%O A131904 1,1
%A A131904 Peter Pein (petsie(AT)dordos.net), Jul 26 2007
%E A131904 More terms from _Michel Marcus_, Apr 03 2015