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 A020927 #21 Mar 25 2022 09:14:12
%S A020927 1,-30,390,-2860,12870,-36036,60060,-51480,12870,2860,1716,1560,1820,
%T A020927 2520,3960,6864,12870,25740,54340,120120,276276,657800,1614600,
%U A020927 4071600,10518300,27768312,74760840,204900080,570793080,1613966640,4626704368,13432367520
%N A020927 Expansion of (1-4*x)^(15/2).
%F A020927 D-finite with recurrence: n*a(n) +2*(-2*n+17)*a(n-1)=0. - _R. J. Mathar_, Jan 17 2020
%F A020927 From _Amiram Eldar_, Mar 25 2022: (Start)
%F A020927 a(n) = (-4)^n*binomial(15/2, n).
%F A020927 Sum_{n>=0} 1/a(n) = 972/1001 + 34*Pi/(3^10*sqrt(3)).
%F A020927 Sum_{n>=0} (-1)^n/a(n) = 18235778692/17595703125 - 68*log(phi)/(5^9*sqrt(5)), where phi is the golden ratio (A001622). (End)
%t A020927 CoefficientList[Series[(1-4x)^(15/2),{x,0,30}],x] (* _Harvey P. Dale_, Oct 03 2012 *)
%Y A020927 Cf. A001622, A002420, A002421, A002422, A002423, A002424, A020923, A020925, A020929.
%K A020927 sign
%O A020927 0,2
%A A020927 _N. J. A. Sloane_