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 A213546 #22 May 12 2025 11:55:02
%S A213546 1,25,170,674,1979,4795,10164,19524,34773,58333,93214,143078,212303,
%T A213546 306047,430312,592008,799017,1060257,1385746,1786666,2275427,2865731,
%U A213546 3572636,4412620,5403645,6565221,7918470,9486190,11292919,13364999,15730640,18419984,21465169
%N A213546 Principal diagonal of the convolution array A213505.
%H A213546 Clark Kimberling, <a href="/A213546/b213546.txt">Table of n, a(n) for n = 1..200</a>
%H A213546 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (6,-15,20,-15,6,-1).
%F A213546 a(n) = (16*n^5 + 15*n^4 - n)/30.
%F A213546 a(n) = 6*a(n-1) - 10*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6).
%F A213546 G.f.: x*(1 + 19*x + 35*x^2 + 9*x^3)/(1 - x)^6.
%F A213546 E.g.f.: exp(x)*x*(30 + 345*x + 490*x^2 + 175*x^3 + 16*x^4)/30. - _Stefano Spezia_, Oct 28 2023
%t A213546 (See A213505.)
%t A213546 LinearRecurrence[{6,-15,20,-15,6,-1},{1,25,170,674,1979,4795},40] (* _Harvey P. Dale_, May 12 2025 *)
%Y A213546 Cf. A213505, A213500.
%K A213546 nonn,easy
%O A213546 1,2
%A A213546 _Clark Kimberling_, Jun 16 2012