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 A306268 #7 Feb 01 2019 21:22:40 %S A306268 1,1,1,0,1,3,1,0,0,3,1,3,1,3,3,0,1,3,1,3,3,3,1,1,0,3,0,3,1,12,1,0,3,3, %T A306268 3,5,1,3,3,1,1,12,1,3,3,3,1,0,0,3,3,3,1,1,3,1,3,3,1,19,1,3,3,0,3,12,1, %U A306268 3,3,12,1,4,1,3,3,3,3,12,1,0,0,3,1,19,3 %N A306268 Number of ways to choose a strict factorization into squarefree factors of each factor in a strict factorization of n. %e A306268 The a(216) = 8 factorizations: %e A306268 (2*3)*(2*3*6) (2*6)*(3*6) %e A306268 (2)*(2*3)*(3*6) (6)*(2*3*6) %e A306268 (2)*(3)*(2*3*6) (2)*(6)*(3*6) %e A306268 (3)*(2*3)*(2*6) (3)*(6)*(2*6) %t A306268 facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]]; %t A306268 Table[Length[Join@@Table[Tuples[Select[facs[#],And[UnsameQ@@#,And@@SquareFreeQ/@#]&]&/@fac],{fac,Select[facs[n],UnsameQ@@#&]}]],{n,60}] %Y A306268 Cf. A001055, A000258, A050326, A050336, A296118, A296120. %K A306268 nonn %O A306268 1,6 %A A306268 _Gus Wiseman_, Feb 01 2019