OFFSET
1,2
COMMENTS
Not multiplicative, for example a(2)*a(3) <> a(6). - R. J. Mathar, Jun 07 2011
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..16385
FORMULA
EXAMPLE
For n = 12, set of such divisors is {2, 3, 6, 12}; a(12) = 1*2*3*6*12 = 432.
MAPLE
isA001694 := proc(n) for p in ifactors(n)[2] do if op(2, p) = 1 then return false; end if; end do; return true; end proc:
A183103 := proc(n) local a, d; a := 1 ; for d in numtheory[divisors](n) do if not isA001694(d) then a := a*d; end if; end do; a ; end proc:
seq(A183103(n), n=1..73) ; # R. J. Mathar, Jun 07 2011
MATHEMATICA
powerfulQ[n_] := Min[FactorInteger[n][[All, 2]]] > 1;
a[n_] := Times @@ Select[Divisors[n], !powerfulQ[#]&];
Table[a[n], {n, 1, 73}] (* Jean-François Alcover, Jun 01 2024 *)
PROG
(PARI) A183103(n) = { my(m=1); fordiv(n, d, if(!ispowerful(d), m *= d)); m; }; \\ Antti Karttunen, Oct 07 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Dec 25 2010
STATUS
approved