A168324 - OEIS

A168324

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

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, 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, 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

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OFFSET

1,6

COMMENTS

Apart from a(1) the same as A008480.

LINKS

Table of n, a(n) for n=1..105.

EXAMPLE

a(18)=3 because 18=2*2*3=2*3*2=3*2*2;

a(24)=4 because 24=2*2*2*3=2*2*3*2=2*3*2*2=3*2*2*2;

a(26)=2 because 26=2*13=13*2;

a(30)=6 because 30=2*3*5=2*5*3=3*2*5=3*5*2=5*2*3=5*3*2.

MATHEMATICA

nn = 105;

f[list_, i] := list[[i]];

a =Table[Boole[PrimeQ[n]], {n, 1, nn}]; Map[Total, Transpose[NestList[Table[

DirichletConvolve[f[#, n], f[a, n], n, m], {m, 1, nn}] &, a, nn]]] (* Geoffrey Critzer, Feb 16 2015 *)

CROSSREFS

Cf. A066882, A008480 (same except for initial term).

Sequence in context: A323087 A321747 A008480 * A355939 A303838 A324837

Adjacent sequences: A168321 A168322 A168323 * A168325 A168326 A168327

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Nov 22 2009, May 08 2010

EXTENSIONS

Entries checked by D. S. McNeil, Nov 26 2010

STATUS

approved