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 A026957 #15 Jun 18 2024 11:09:23
%S A026957 1,6,35,154,613,2362,9028,34510,132241,508210,1958460,7565906,
%T A026957 29292820,113633930,441579702,1718642278,6698377449,26139863330,
%U A026957 102125977396,399415127682,1563614796608,6126581578954,24024810462810,94281930087290,370254213115948,1454967778894282
%N A026957 a(n) = Sum_{k=0..n-1} T(n,k) * T(n,k+1), with T given by A026615.
%H A026957 G. C. Greubel, <a href="/A026957/b026957.txt">Table of n, a(n) for n = 1..1000</a>
%F A026957 a(n) = (n-1)*binomial(2*n, n-1)*(49*n^3 - 105*n^2 + 62*n - 24 )/( 24*binomial(2*n, 4)) - 2*(2*n-1), for n >= 2, with a(1) = 1. - _G. C. Greubel_, Jun 17 2024
%t A026957 Table[If[n==1, 1, (n-1)*Binomial[2*n,n-1]*(49*n^3 -105*n^2 +62*n -24 )/(24*Binomial[2*n,4]) - 2*(2*n-1)], {n,40}] (* _G. C. Greubel_, Jun 17 2024 *)
%o A026957 (Magma) [1] cat [(n-1)*Binomial(2*n,n-1)*(49*n^3 -105*n^2 +62*n -24)/( 24*Binomial(2*n,4)) -2*(2*n-1): n in [2..40]]; // _G. C. Greubel_, Jun 17 2024
%o A026957 (SageMath) [1]+[(n-1)*binomial(2*n,n-1)*(49*n^3-105*n^2+62*n-24 )/( 24*binomial(2*n, 4)) -2*(2*n-1) for n in range(2,41)] # _G. C. Greubel_, Jun 17 2024
%Y A026957 Cf. A026615, A026616, A026617, A026618, A026619, A026620, A026621.
%Y A026957 Cf. A026622, A026623, A026624, A026625, A026956, A026958, A026959.
%Y A026957 Cf. A026960.
%K A026957 nonn
%O A026957 1,2
%A A026957 _Clark Kimberling_
%E A026957 More terms from _Sean A. Irvine_, Oct 20 2019