%I #8 Nov 13 2021 16:44:03
%S 1,2,4,12,36,144,576,2880,14400,100800,705600,6350400,45158400,
%T 406425600,3657830400,40236134400,442597478400,5753767219200,
%U 74798973849600,1271582555443200,21616903442534400,410721165408153600,7803702142754918400,179485149283363123200,4128158433517351833600
%N a(n) is the least k such that A349281(k) = n.
%H Amiram Eldar, <a href="/A349282/b349282.txt">Table of n, a(n) for n = 0..40</a>
%e a(2) = 4 since A349281(4) = 2 and A349281(k) != 2 for all k < 4.
%t f[p_, e_] := DivisorSigma[0, e]; d[1] = 0; d[n_] := Plus @@ f @@@ FactorInteger[n]; seq[len_, nmax_] := Module[{s = Table[0, {len}], k = 0, n = 1, i}, While[k < len && n < nmax, i = d[n] + 1; If[i <= len && s[[i]] == 0, k++; s[[i]] = n]; n++]; TakeWhile[s, # > 0 &]]; seq[11, 10^6]
%Y Cf. A349260, A349281.
%Y Subsequence of A025487.
%K nonn
%O 0,2
%A _Amiram Eldar_, Nov 13 2021