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 A213807 #12 Jun 21 2012 17:51:25 %S A213807 0,0,6,50,295,1450,6706,29790,129900,559680,2395701,10212620,43430140, %T A213807 184412740,782337466,3317046390,14059122315,59576034630,252422169726, %U A213807 1069418901650,4530501461200,19192481509300,81303194179081,344412501233400,1458972161656920 %N A213807 a(n)=Sum(L(i)*L(j)*L(k), 0<=i<j<k<=n), where L(m) is the m-th Lucas number A000032(m). %C A213807 This is to Lucas numbers A000032 as A213787 is to Fibonacci numbers A000045. %H A213807 Alois P. Heinz, <a href="/A213807/b213807.txt">Table of n, a(n) for n = 0..500</a> %F A213807 G.f.: -(x^6-19*x^5+4*x^4+53*x^3+7*x^2-8*x-6)*x^2 / ((x-1) * (x+1) * (x^2-x-1) * (x^2+x-1)*(x^2+4*x-1)*(x^2-3*x+1)). - _Alois P. Heinz_, Jun 21 2012 %p A213807 a:= n-> (Matrix(10, (i, j)-> `if`(i=j-1, 1, `if`(i=10, %p A213807 [-1, -1, 16, -3, -51, 24, 45, -27, -8, 7][j], 0)))^(n+3). %p A213807 <<-20, 1, 0, 0, 0, 6, 50, 295, 1450, 6706>>)[1, 1]: %p A213807 seq (a(n), n=0..30); # _Alois P. Heinz_, Jun 21 2012 %Y A213807 Cf. A000032, A213787. %K A213807 nonn,easy %O A213807 0,3 %A A213807 _Jonathan Vos Post_, Jun 20 2012