login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A327521 Number of factorizations of the n-th squarefree number A005117(n) into squarefree numbers > 1. 0
1, 1, 1, 1, 2, 1, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 2, 1, 5, 1, 2, 2, 2, 1, 2, 2, 1, 5, 1, 2, 1, 2, 1, 2, 2, 2, 1, 1, 2, 2, 5, 1, 2, 5, 1, 1, 2, 2, 5, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 1, 1, 5, 1, 5, 2, 1, 1, 5, 2, 1, 5, 2, 2, 2, 2, 2, 1, 2, 5, 1, 2, 2, 1, 5, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..87.

Gus Wiseman, Sequences counting and encoding certain classes of multisets

FORMULA

a(n) = A050320(A005117(n)) = A000110(A072047(n)) = A000110(A001222(A005117(n))).

MATHEMATICA

nn=100;

facsusing[s_, n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[facsusing[Select[s, Divisible[n/d, #]&], n/d], Min@@#>=d&]], {d, Select[s, Divisible[n, #]&]}]];

y=Select[Range[nn], SquareFreeQ];

Table[Length[facsusing[Rest[y], n]], {n, y}]

CROSSREFS

See link for additional cross-references.

Cf. A000110, A005117, A007947, A034444, A050320, A072047, A259936.

Sequence in context: A329618 A026517 A072047 * A282870 A106802 A269254

Adjacent sequences:  A327518 A327519 A327520 * A327522 A327523 A327524

KEYWORD

nonn

AUTHOR

Gus Wiseman, Sep 15 2019

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 17 22:15 EDT 2021. Contains 343992 sequences. (Running on oeis4.)