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 A023620 #19 Jan 15 2023 09:53:07 %S A023620 1,6,18,41,82,152,269,462,778,1293,2130,3488,5689,9254,15026,24369, %T A023620 39490,63960,103557,167630,271306,439061,710498,1149696,1860337, %U A023620 3010182,4870674,7881017,12751858,20633048,33385085,54018318,87403594,141422109,228825906 %N A023620 Convolution of Lucas numbers and odd numbers. %H A023620 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (3,-2,-1,1). %F A023620 a(n) = L(5)*(F(n+1)-1) + L(4)*F(n) - L(3)*n - 2*n, F(n) = A000045(n). %F A023620 a(n) = A033811(n) - 2n. - _N. J. A. Sloane_, Jun 12 2004 %F A023620 a(n) = 3*a(n-1)-2*a(n-2)-a(n-3)+a(n-4). G.f.: -x*(x+1)*(2*x+1) / ((x-1)^2*(x^2+x-1)). - _Colin Barker_, May 14 2014 %o A023620 (PARI) Vec(-x*(x+1)*(2*x+1)/((x-1)^2*(x^2+x-1)) + O(x^100)) \\ _Colin Barker_, May 14 2014 %Y A023620 Cf. A000023, A000045, A033811. %K A023620 nonn,easy %O A023620 1,2 %A A023620 _Clark Kimberling_, Jun 14 1998 %E A023620 More terms from _Colin Barker_, May 14 2014