This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A187811 #13 Jan 26 2016 19:22:14 %S A187811 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 A187811 43,44,45,46,47,48,49,51,54,55,56,57,59,60,62,63,66,67,69,70,71,72,75, %U A187811 76,77,78,79,81,83,84,86,87,88,90,91,92,93,94,95,96,98,99 %N A187811 Numbers having at least one prime factor of form 4*k+3. %C A187811 A005091(a(n)) > 0. - _Reinhard Zumkeller_, Jan 07 2013 %H A187811 Reinhard Zumkeller, <a href="/A187811/b187811.txt">Table of n, a(n) for n = 1..10000</a> %F A187811 a(n) ~ n. - _Charles R Greathouse IV_, Sep 01 2015 %t A187811 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 A187811 (Haskell) %o A187811 import Data.List (findIndices) %o A187811 a187811 n = a187811_list !! (n-1) %o A187811 a187811_list = map (+ 1) $ findIndices (> 0) a005091_list %o A187811 -- _Reinhard Zumkeller_, Jan 07 2013 %o A187811 (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 A187811 Cf. A072437 (complement); A002145, A009003. %K A187811 nonn %O A187811 1,1 %A A187811 _Reinhard Zumkeller_, Jan 07 2013