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 A259969 #19 Jun 28 2017 17:16:24 %S A259969 0,1,2,9,24,50,102,210,424,837,1630,3146,6024,11453,21644,40695,76176, %T A259969 142035,263916,488870,903060,1663998,3059166,5612483,10277448, %U A259969 18787150,34287916,62485371,113715448,206683725,375211710,680399005,1232533696,2230537914 %N A259969 a(n) = n*A259968(n). %D A259969 R. K. Guy, Letter to N. J. A. Sloane, Feb 05 1986. %H A259969 Colin Barker, <a href="/A259969/b259969.txt">Table of n, a(n) for n = 0..1000</a> %H A259969 R. K. Guy, <a href="/A005251/a005251.pdf">Letter to N. J. A. Sloane, Feb 1986</a> %H A259969 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,6,-5,2,-1). %F A259969 G.f.: x*(x^4-6*x^3+7*x^2-2*x+1) / (x^3-x^2+2*x-1)^2. - _Colin Barker_, Jul 12 2015 %o A259969 (PARI) concat(0, Vec(x*(x^4-6*x^3+7*x^2-2*x+1)/(x^3-x^2+2*x-1)^2 + O(x^40))) \\ _Colin Barker_, Jul 12 2015 %o A259969 (Haskell) %o A259969 a259967 n = a259967_list !! n %o A259969 a259967_list = 3 : 2 : 2 : 5 : zipWith3 (((+) .) . (+)) %o A259969 a259967_list (drop 2 a259967_list) (drop 3 a259967_list) %o A259969 -- _Reinhard Zumkeller_, Jul 12 2015 %Y A259969 Cf. A259968, A259967. %K A259969 nonn,easy %O A259969 0,3 %A A259969 _N. J. A. Sloane_, Jul 11 2015 %E A259969 a(28)-a(33) from _Hiroaki Yamanouchi_, Jul 12 2015