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%I #13 Sep 05 2018 15:40:18
%S 0,0,0,1,1,1,1,2,3,3,3,3,3,3,3,4,4,5,5,5,5,5,5,5,6,6,7,7,7,7,7,8,8,8,
%T 8,9,9,9,9,9,9,9,9,9,9,9,9,9,10,11,11,11,11,12,12,12,12,12,12,12,12,
%U 12,12,13,13,13,13,13,13,13,13,14,14,14,15,15,15,15,15,15,16
%N Partial sums of the characteristic function for A070003.
%C a(n) tells how many natural numbers <= n there are which are divisible by the square of their largest prime divisor. (This definition excludes 1 as it has no prime divisors.)
%C For all n, a(A070003(n)) = n, thus this sequence works also as an inverse function for the injection A070003.
%H Harvey P. Dale, <a href="/A243282/b243282.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = A243283(n)-1.
%e A070003(402) = 10000, thus a(10000) = 402.
%t Accumulate[Join[{0},Table[If[Divisible[n,Last[Select[Divisors[n],PrimeQ]]^2],1,0],{n,2,90}]]] (* _Harvey P. Dale_, Sep 05 2018 *)
%o (define (A243282 n) (- (A243283 n) 1))
%Y One less than A243283.
%Y Cf. A070003, A243285.
%K nonn
%O 1,8
%A _Antti Karttunen_, Jun 02 2014