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 A190891 #4 Mar 30 2012 18:57:29 %S A190891 4,8,12,21,25,29,38,42,46,50,55,59,63,67,72,76,80,84,93,97,101,110, %T A190891 114,118,122,127,131,135,139,144,148,152,156,165,169,173,182,186,190, %U A190891 199,203,207,211,216,220,224,228,237,241,245,254,258,262,271,275,279,283,288,292,296,300,309,313,317,326,330,334,343,347,351,355 %N A190891 Positions of 4 in A190886. %C A190891 See A190886. %t A190891 (See A190886.) %Y A190891 Cf. A190886. %K A190891 nonn %O A190891 1,1 %A A190891 _Clark Kimberling_, May 26 2011