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a(n) = 1 if n is divisible by the square of its largest prime factor, 0 otherwise.
11

%I #12 Sep 19 2022 11:51:00

%S 0,0,0,1,0,0,0,1,1,0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,1,0,1,0,0,0,0,1,0,0,

%T 0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,

%U 0,0,0,1,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1

%N a(n) = 1 if n is divisible by the square of its largest prime factor, 0 otherwise.

%H Antti Karttunen, <a href="/A319988/b319988.txt">Table of n, a(n) for n = 1..65537</a>

%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

%F a(n) = 1 iff A071178(n) > 1.

%F a(n) = 1 if n > 1 and A006530(n)^2 divides n, otherwise 0.

%F a(n) = 1 iff n > 1 and A241917(n) = 0.

%F For n > 1, a(n) = A000035(A336124(n)) = A122111(n) mod 2. - _Antti Karttunen_, Jul 18 2020

%t Join[{0},Table[If[Divisible[n,FactorInteger[n][[-1,1]]^2],1,0],{n,2,130}]] (* _Harvey P. Dale_, Sep 19 2022 *)

%o (PARI) A319988(n) = ((n>1)&&(factor(n)[omega(n),2]>1));

%Y Characteristic function of A070003.

%Y Cf. A006530, A071178, A122111, A241917, A319710, A336124.

%K nonn

%O 1

%A _Antti Karttunen_, Oct 04 2018