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 A123259 #5 Jul 20 2016 12:18:46 %S A123259 3,-7,11,233,-3357,25673,-102709,-319207,9893763,-97727527,563250251, %T A123259 -818302327,-23939051037,331342081193,-2482627432309,9536407068473, %U A123259 35533850058243,-988203251837767,9543386061052811,-53687973726459607,64388654104236003,2442458092308867593 %N A123259 A123228/2. %H A123259 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (-13,-74,-74,-13,-1). %o A123259 (PARI) polsym(x^6 + 14*x^5 + 87*x^4 + 148*x^3 + 87*x^2 + 14*x + 1, 30)/2 \\ _Charles R Greathouse IV_, Jul 20 2016 %K A123259 sign,easy %O A123259 0,1 %A A123259 _N. J. A. Sloane_, Nov 12 2006