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 A113440 #11 Jul 20 2024 19:14:41
%S A113440 1,2,8,34,146,627,2689,11521,49337,211233,904306,3871305,16572812,
%T A113440 70947073,303719624,1300203634,5566087073,23828058969,102006385362,
%U A113440 436682772844,1869410868456,8002827727921,34259590954322
%N A113440 First row of A113439.
%H A113440 G. C. Greubel, <a href="/A113440/b113440.txt">Table of n, a(n) for n = 0..1000</a>
%H A113440 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (9,-28,38,-20,1).
%F A113440 a(n) = A113439(4*n).
%F A113440 a(n) = 9*a(n-1) - 28*a(n-2) + 38*a(n-3) - 20*a(n-4) + a(n-5).
%F A113440 G.f.: -(1-7*x+18*x^2-20*x^3+8*x^4)/(-1+9*x-28*x^2+38*x^3-20*x^4+x^5).
%t A113440 CoefficientList[Series[-(1 - 7*x + 18*x^2 - 20*x^3 + 8*x^4)/(-1 + 9*x - 28*x^2 + 38*x^3 - 20*x^4 + x^5), {x,0,50}], x] (* _G. C. Greubel_, Mar 11 2017 *)
%t A113440 LinearRecurrence[{9,-28,38,-20,1},{1,2,8,34,146},30] (* _Harvey P. Dale_, Jul 20 2024 *)
%o A113440 (PARI) x='x+O('x^50); Vec(-(1-7*x+18*x^2-20*x^3+8*x^4)/(-1+9*x-28*x^2+38*x^3-20*x^4+x^5)) \\ _G. C. Greubel_, Mar 11 2017
%Y A113440 Cf. A113439.
%K A113440 nonn,easy
%O A113440 0,2
%A A113440 _Floor van Lamoen_, Nov 04 2005