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 A213767 #18 Jul 10 2019 12:10:44 %S A213767 1,5,17,47,114,254,533,1071,2083,3951,7348,13452,24313,43481,77077, %T A213767 135615,237094,412234,713325,1229155,2110151,3610655,6159912,10481112, %U A213767 17790769,30132269,50933273,85936271,144750618,243438806 %N A213767 Antidiagonal sums of the convolution array A213765. %H A213767 Clark Kimberling, <a href="/A213767/b213767.txt">Table of n, a(n) for n = 1..500</a> %H A213767 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (4,-4,-2,4,0,-1). %F A213767 a(n) = 4*a(n-1)-4*a(n-2)-2*a(n-3)+4*a(n-4)-a(n-6). %F A213767 G.f.: f(x)/g(x), where f(x) = x*(1 + x + x^2 + x^3) and g(x) = (1 - 2*x + x^3)^2. %F A213767 a(n) = n*Fibonacci(n+5) - Lucas(n+6) + 2*(2*n+9). - _Ehren Metcalfe_, Jul 10 2019 %t A213767 (See A213765.) %Y A213767 Cf. A213765, A213500. %K A213767 nonn,easy %O A213767 1,2 %A A213767 _Clark Kimberling_, Jun 21 2012