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A221265 Numbers having more distinct prime factors of form 4*k+1 than of 4*k+3. 5


%S 5,10,13,17,20,25,26,29,34,37,40,41,50,52,53,58,61,65,68,73,74,80,82,

%T 85,89,97,100,101,104,106,109,113,116,122,125,130,136,137,145,146,148,

%U 149,157,160,164,169,170,173,178,181,185,193,194,195,197,200,202

%N Numbers having more distinct prime factors of form 4*k+1 than of 4*k+3.

%C A005089(a(n)) > A005091(a(n)); a005094(a(n)) > 0.

%H Reinhard Zumkeller, <a href="/A221265/b221265.txt">Table of n, a(n) for n = 1..10000</a>

%t mdpf1Q[n_]:=Module[{f=Transpose[FactorInteger[n]][[1]]},Count[f,_?(Mod[ #,4] == 1&)]>Count[f,_?(Mod[#,4]==3&)]]; Select[Range[2,250],mdpf1Q] (* _Harvey P. Dale_, Mar 03 2016 *)

%o (Haskell)

%o a221265 n = a221265_list !! (n-1)

%o a221265_list = filter ((> 0) . a005094) [1..]

%Y Cf. A078613, A221264.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Jan 07 2013

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Last modified December 9 03:27 EST 2019. Contains 329872 sequences. (Running on oeis4.)