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 A191931 #7 Nov 21 2013 12:50:18
%S A191931 0,1,3,5,8,9,10,11,12,13,15,17,21,24,25,26,27,33,37,40,41,43,54,61,65,
%T A191931 68,69,71,87,98,105,109,112,113,115,141,159,170,177,181,184,185,187,
%U A191931 228,257,275,286,293,297,300,301,303,369,416,445,463,474,481,485
%N A191931 Ordered sequence of nonnegative differences 4f-g, where f and g are Lucas numbers (A000032 beginning at 1).
%t A191931 (See A191929.)
%t A191931 Take[Union[Select[4First[#]-Last[#]&/@Tuples[LucasL[Range[20]],{2}], #>=0&]],70] (* _Harvey P. Dale_, Aug 21 2011 *)
%Y A191931 Cf. A191929, A191930, A191932.
%K A191931 nonn
%O A191931 1,3
%A A191931 _Clark Kimberling_, Jun 19 2011