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 A213754 #22 Nov 07 2017 07:31:47 %S A213754 1,16,111,576,2631,11292,46927,191680,775599,3122076,12531591, %T A213754 50220912,201088855,804798268,3220143903,12882607872,51534757599, %U A213754 206148206268,824612224663,3298489794160,13194045161031,52776361000476 %N A213754 Principal diagonal of the convolution array A213753. %H A213754 Clark Kimberling, <a href="/A213754/b213754.txt">Table of n, a(n) for n = 1..1000</a> %H A213754 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (11,-47,101,-116,68,-16). %F A213754 a(n) = -3*2^n + 3*2^(2*n) - n*2^(n+1) - n^2. %F A213754 a(n) = 11*a(n-1) - 47*a(n-2) + 101*a(n-3) - 116*a(n-4) + 68*a(n-5) - 16*a(n-6) for n>5. Corrected by _Colin Barker_, Nov 07 2017 %F A213754 G.f.: f(x)/g(x), where f(x) = x*(1 + 5*x - 18*x^2 + 6*x^3 + 12*x^4) and g(x) = (1 - 4*x) * (1 - x)^3 * (1 - 2*x)^2. %t A213754 (See A213753.) %o A213754 (PARI) Vec(x*(1 + 5*x - 18*x^2 + 6*x^3 + 12*x^4) / ((1 - x)^3*(1 - 2*x)^2*(1 - 4*x)) + O(x^30)) \\ _Colin Barker_, Nov 07 2017 %Y A213754 Cf. A213753, A213500. %K A213754 nonn,easy %O A213754 1,2 %A A213754 _Clark Kimberling_, Jun 20 2012