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%I #13 Jan 26 2016 19:22:14
%S 3,6,7,9,11,12,14,15,18,19,21,22,23,24,27,28,30,31,33,35,36,38,39,42,
%T 43,44,45,46,47,48,49,51,54,55,56,57,59,60,62,63,66,67,69,70,71,72,75,
%U 76,77,78,79,81,83,84,86,87,88,90,91,92,93,94,95,96,98,99
%N Numbers having at least one prime factor of form 4*k+3.
%C A005091(a(n)) > 0. - _Reinhard Zumkeller_, Jan 07 2013
%H Reinhard Zumkeller, <a href="/A187811/b187811.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) ~ n. - _Charles R Greathouse IV_, Sep 01 2015
%t pfQ[n_]:=AnyTrue[Transpose[FactorInteger[n]][[1]],Mod[#,4]==3&]; Select[ Range[100],pfQ] (* The program uses the AnyTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Jan 26 2016 *)
%o (Haskell)
%o import Data.List (findIndices)
%o a187811 n = a187811_list !! (n-1)
%o a187811_list = map (+ 1) $ findIndices (> 0) a005091_list
%o -- _Reinhard Zumkeller_, Jan 07 2013
%o (PARI) is(n)=if(n%4==3,return(1)); my(f=factor(n)[,1]%4); for(i=1,#f, if(f[i]==3, return(1))); 0 \\ _Charles R Greathouse IV_, Sep 01 2015
%Y Cf. A072437 (complement); A002145, A009003.
%K nonn
%O 1,1
%A _Reinhard Zumkeller_, Jan 07 2013
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