cp's OEIS Frontend

A340851 Number of factorizations of n such that every factor is a divisor of the number of factors.

%I A340851 #6 Feb 04 2021 20:53:21
%S A340851 1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1,0,0,
%T A340851 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,
%U A340851 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
%N A340851 Number of factorizations of n such that every factor is a divisor of the number of factors.
%C A340851 Also factorizations whose number of factors is divisible by their least common multiple.
%e A340851 The a(n) factorizations for n = 8192, 46656, 73728:
%e A340851   2*2*2*2*2*4*8*8          6*6*6*6*6*6              2*2*2*2*2*2*2*2*2*4*6*6
%e A340851   2*2*2*2*4*4*4*8          2*2*2*2*2*2*3*3*3*3*3*3  2*2*2*2*2*2*2*2*3*4*4*6
%e A340851   2*2*2*4*4*4*4*4                                   2*2*2*2*2*2*2*3*3*4*4*4
%e A340851   2*2*2*2*2*2*2*2*2*2*2*4                           2*2*2*2*2*2*2*2*2*2*6*12
%e A340851                                                     2*2*2*2*2*2*2*2*2*3*4*12
%t A340851 facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]];
%t A340851 Table[Length[Select[facs[n],And@@IntegerQ/@(Length[#]/#)&]],{n,100}]
%Y A340851 The version for partitions is A340693, with reciprocal version A143773.
%Y A340851 Positions of nonzero terms are A340852.
%Y A340851 The reciprocal version is A340853.
%Y A340851 A320911 can be factored into squarefree semiprimes.
%Y A340851 A340597 have an alt-balanced factorization.
%Y A340851 A340656 lack a twice-balanced factorization, complement A340657.
%Y A340851 - Factorizations -
%Y A340851 A001055 counts factorizations, with strict case A045778.
%Y A340851 A316439 counts factorizations by product and length.
%Y A340851 A339846 counts factorizations of even length.
%Y A340851 A339890 counts factorizations of odd length.
%Y A340851 A340101 counts factorizations into odd factors, odd-length case A340102.
%Y A340851 A340653 counts balanced factorizations.
%Y A340851 A340785 counts factorizations into even numbers, even-length case A340786.
%Y A340851 A340831/A340832 count factorizations with odd maximum/minimum.
%Y A340851 A340854 cannot be factored with odd least factor, complement A340855.
%Y A340851 Cf. A067538, A074761, A168659, A301987, A327517, A340596, A340599, A340654, A340655, A340827, A340830.
%K A340851 nonn
%O A340851 1,64
%A A340851 _Gus Wiseman_, Feb 04 2021