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 A084151 #12 Oct 11 2022 07:40:56
%S A084151 0,0,1,9,62,390,2359,14007,82412,482652,2820061,16457397,95983370,
%T A084151 559619970,3262267891,19015581699,110836005272,646014798840,
%U A084151 3765295834489,21945889348257,127910427675542,745517838966462
%N A084151 Binomial transform of a Pell convolution.
%C A084151 Binomial transform of A006668. Second binomial transform of A084150.
%H A084151 G. C. Greubel, <a href="/A084151/b084151.txt">Table of n, a(n) for n = 0..1000</a>
%H A084151 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (9,-19,3).
%F A084151 a(n) = ( (3+sqrt(8))^n + (3-sqrt(8))^n - 2*3^n )/16.
%F A084151 E.g.f.: (1/4)*exp(3*x)*( sinh(sqrt(2)*x) )^2.
%F A084151 G.f.: x^2 / ( (1-3*x)*(1-6*x+x^2) ). - _R. J. Mathar_, Sep 27 2012
%F A084151 a(n) = (A001541(n) - 3^n)/8. - _R. J. Mathar_, Sep 27 2012
%F A084151 a(n) = (1/8)*(ChebyshevT(n, 3) - 3^n) = (A001541(n) - A000244(n))/8. - _G. C. Greubel_, Oct 11 2022
%t A084151 LinearRecurrence[{9,-19,3},{0,0,1},30] (* _Harvey P. Dale_, Jun 06 2021 *)
%o A084151 (Magma) [(Evaluate(ChebyshevFirst(n), 2) -3^n)/8: n in [0..40]]; // _G. C. Greubel_, Oct 11 2022
%o A084151 (SageMath) [(chebyshev_T(n, 3) - 3^n)/8 for n in range(41)] # _G. C. Greubel_, Oct 11 2022
%Y A084151 Cf. A000244, A001541, A006668, A084150.
%K A084151 easy,nonn
%O A084151 0,4
%A A084151 _Paul Barry_, May 16 2003