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 A064331 #10 Sep 08 2022 08:45:04
%S A064331 1,1,-8,145,-3266,82342,-2223818,62912809,-1840413050,55217088622,
%T A064331 -1689752866904,52538652432586,-1655036407913948,52708355827445800,
%U A064331 -1694246075896308110,54894923324331676345,-1790984858946499478330
%N A064331 Generalized Catalan numbers C(-9; n).
%C A064331 See triangle A064334 with columns m built from C(-m; n), m >= 0, also for Derrida et al. references.
%H A064331 G. C. Greubel, <a href="/A064331/b064331.txt">Table of n, a(n) for n = 0..640</a>
%F A064331 a(n) = Sum_{m=0..n-1} (n-m)*binomial(n-1+m, m)*(-9)^m/n.
%F A064331 a(n) = (1/10)^n*(1 + 9*Sum_{k=0..n-1} C(k)*(-9*10)^k ), n >= 1, a(0) := 1; with C(n)=A000108(n) (Catalan).
%F A064331 G.f.: (1+9*x*c(-9*x)/10)/(1-x/10) = 1/(1-x*c(-9*x)) with c(x) g.f. of Catalan numbers A000108.
%t A064331 CoefficientList[Series[(19 +Sqrt[1+36*x])/(2*(10-x)), {x, 0, 30}], x] (* _G. C. Greubel_, May 03 2019 *)
%o A064331 (PARI) my(x='x+O('x^30)); Vec((19 +sqrt(1+36*x))/(2*(10-x))) \\ _G. C. Greubel_, May 03 2019
%o A064331 (Magma) R<x>:=PowerSeriesRing(Rationals(), 30); Coefficients(R!( (19 +Sqrt(1+36*x))/(2*(10-x)) )); // _G. C. Greubel_, May 03 2019
%o A064331 (Sage) ((19 +sqrt(1+36*x))/(2*(10-x))).series(x, 30).coefficients(x, sparse=False) # _G. C. Greubel_, May 03 2019
%K A064331 sign,easy
%O A064331 0,3
%A A064331 _Wolfdieter Lang_, Sep 21 2001