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%I #10 Jun 22 2020 04:48:35
%S 1,1,1,1,1,2,1,1,1,2,2,1,1,2,1,1,1,2,3,1,1,1,1,3,1,1,2,3,2,2,1,2,1,2,
%T 1,2,2,1,2,1,1,4,1,2,1,1,3,2,1,3,3,1,2,2,1,3,2,1,1,4,1,1,1,2,4,1,2,1,
%U 1,1,2,2,2,3,3,2,3,1,3,3,1,2,3,1,2,2,1,1,4,1,1,1,2,1,4,1,1,3,4,1,1,2
%N Number of semiprime divisors of n-th composite number.
%H Robert Israel, <a href="/A088737/b088737.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A056170(n) + A001221(n)*(A001221(n)-1)/2.
%p f:= proc(n) local p, t;
%p p:= numtheory:-factorset(n);
%p t:= nops(p);
%p t*(t-1)/2 + nops(select(m-> n mod m^2=0, p))
%p end proc:
%p map(f, remove(isprime,[$4..200])); # _Robert Israel_, May 21 2020
%t a[n_] := Count[FactorInteger[n], {_, k_ /; k>1}]+PrimeNu[n](PrimeNu[n]-1)/2;
%t a /@ Select[Range[200], CompositeQ] (* _Jean-François Alcover_, Jun 22 2020 *)
%Y Cf. A088738, A002808, A001358.
%K nonn
%O 1,6
%A _Reinhard Zumkeller_, Oct 12 2003
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