cp's OEIS Frontend

A168324 Number of distinct permutations of the list of prime factors of n (with multiplicity), where a(1)=0.

%I A168324 #17 Apr 28 2022 08:53:12
%S A168324 0,1,1,1,1,2,1,1,1,2,1,3,1,2,2,1,1,3,1,3,2,2,1,4,1,2,1,3,1,6,1,1,2,2,
%T A168324 2,6,1,2,2,4,1,6,1,3,3,2,1,5,1,3,2,3,1,4,2,4,2,2,1,12,1,2,3,1,2,6,1,3,
%U A168324 2,6,1,10,1,2,3,3,2,6,1,5,1,2,1,12,2,2,2,4,1,12,2,3,2,2,2,6,1,3,3,6,1,6,1,4,6
%N A168324 Number of distinct permutations of the list of prime factors of n (with multiplicity), where a(1)=0.
%C A168324 Apart from a(1) the same as A008480.
%e A168324 a(18)=3 because 18=2*2*3=2*3*2=3*2*2;
%e A168324 a(24)=4 because 24=2*2*2*3=2*2*3*2=2*3*2*2=3*2*2*2;
%e A168324 a(26)=2 because 26=2*13=13*2;
%e A168324 a(30)=6 because 30=2*3*5=2*5*3=3*2*5=3*5*2=5*2*3=5*3*2.
%t A168324 nn = 105;
%t A168324 f[list_, i] := list[[i]];
%t A168324 a =Table[Boole[PrimeQ[n]], {n, 1, nn}]; Map[Total,Transpose[NestList[Table[
%t A168324 DirichletConvolve[f[#, n], f[a, n], n, m], {m, 1, nn}] &, a,nn]]] (* _Geoffrey Critzer_, Feb 16 2015 *)
%Y A168324 Cf. A066882, A008480 (same except for initial term).
%K A168324 nonn
%O A168324 1,6
%A A168324 _Juri-Stepan Gerasimov_, Nov 22 2009, May 08 2010
%E A168324 Entries checked by _D. S. McNeil_, Nov 26 2010