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%I #7 Jun 02 2012 17:06:59
%S 10,20,26,30,34,40,50,52,58,60,68,70,74,78,80,82,90,100,102,104,106,
%T 110,116,120,122,130,136,140,146,148,150,156,160,164,170,174,178,180,
%U 182,190,194,200,202,204,208,210,212,218,220,222,226,230,232,234,238
%N Even numbers with at least one prime factor of form 4*k+1.
%C A072591(a(n)) = 0.
%C Conjecture: this is exactly the sequence whose terms are twice those of A009003. (This has been verified for all terms<=500.) Compare A009003. - _John W. Layman_, Mar 12 2008
%C The conjecture is true. See comments on A008846 and A004613. - Lambert Herrgesell (zero815(AT)googlemail.com), Apr 24 2008
%H Harvey P. Dale, <a href="/A072592/b072592.txt">Table of n, a(n) for n = 1..1000</a>
%t opfQ[n_]:=Count[Transpose[FactorInteger[n]][[1]],_?(IntegerQ[ (#-1)/4]&)]>0; Select[Range[2,250,2],opfQ] (* _Harvey P. Dale_, Jun 02 2012 *)
%Y Cf. A005843, A002144.
%K nonn
%O 1,1
%A _Reinhard Zumkeller_, Jun 23 2002
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