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 A077885 #5 May 29 2018 13:52:01 %S A077885 1,1,1,3,3,3,7,7,7,15,15,15,31,31,31,63,63,63,127,127,127,255,255,255, %T A077885 511,511,511,1023,1023,1023,2047,2047,2047,4095,4095,4095,8191,8191, %U A077885 8191,16383,16383,16383,32767,32767,32767,65535,65535,65535,131071,131071,131071,262143 %N A077885 Expansion of (1-x)^(-1)/(1-2*x^3). %H A077885 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,2,-2). %K A077885 nonn,easy %O A077885 0,4 %A A077885 _N. J. A. Sloane_, Nov 17 2002