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 A358252 #14 Nov 06 2022 03:17:06 %S A358252 1,8,32,128,288,864,1152,2592,4608,13824,10368,20736,28800,41472, %T A358252 64800,279936,115200,331776,345600,663552,259200,1679616,518400, %U A358252 1620000,1166400,4860000,1036800,17915904,2073600,15552000,6998400,26873856,4147200,53747712,8294400 %N A358252 a(n) is the least number with exactly n non-unitary square divisors. %C A358252 a(n) is the least number k such that A056626(k) = n. %C A358252 Since A056626(k) depends only on the prime signature of k, all the terms of this sequence are in A025487. %H A358252 Amiram Eldar, <a href="/A358252/b358252.txt">Table of n, a(n) for n = 0..176</a> %e A358252 a(1) = 8 since 8 is the least number that has exactly one non-unitary square divisor, 4. %t A358252 f1[p_, e_] := 1 + Floor[e/2]; f2[p_, e_] := 2^(1 - Mod[e, 2]); f[1] = 0; f[n_] := Times @@ f1 @@@ (fct = FactorInteger[n]) - Times @@ f2 @@@ fct; seq[len_, nmax_] := Module[{s = Table[0, {len}], c = 0, n = 1, i}, While[c < len && n < nmax, i = f[n] + 1; If[i <= len && s[[i]] == 0, c++; s[[i]] = n]; n++]; s]; seq[21, 10^6] %o A358252 (PARI) s(n) = {my(f = factor(n)); prod(i = 1, #f~, 1 + floor(f[i,2]/2)) - 2^sum(i = 1, #f~, 1 - f[i,2]%2);} %o A358252 lista(len, nmax) = {my(v = vector(len), c = 0, n = 1, i); while(c < len && n < nmax, i = s(n) + 1; if(i <= len && v[i] == 0, c++; v[i] = n); n++); v}; %Y A358252 Cf. A056626, A025487, A358253. %Y A358252 Similar sequences: A005179 (all divisors), A038547 (odd divisors), A085629 (coreful divisors), A130279 (square), A187941 (even), A309181 (non-unitary), A340232 (bi-unitary), A340233 (exponential), A357450 (odd square). %K A358252 nonn %O A358252 0,2 %A A358252 _Amiram Eldar_, Nov 05 2022