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A020931 Expansion of (1-4*x)^(19/2). 2

%I #16 Mar 25 2022 09:14:29

%S 1,-38,646,-6460,41990,-184756,554268,-1108536,1385670,-923780,184756,

%T 33592,16796,12920,12920,15504,21318,32604,54340,97240,184756,369512,

%U 772616,1679600,3779100,8767512,20907144,51106352,127765880,326023280,847660528,2242198816

%N Expansion of (1-4*x)^(19/2).

%F D-finite with recurrence: n*a(n) +2*(-2*n+21)*a(n-1)=0. - _R. J. Mathar_, Jan 17 2020

%F From _Amiram Eldar_, Mar 25 2022: (Start)

%F a(n) = (-4)^n*binomial(19/2, n).

%F Sum_{n>=0} 1/a(n) = 45052/46189 + 14*Pi/(3^11*sqrt(3)).

%F Sum_{n>=0} (-1)^n/a(n) = 6955761045148/6765966796875 - 84*log(phi)/(5^11*sqrt(5)), where phi is the golden ratio (A001622). (End)

%t CoefficientList[Series[(1-4x)^(19/2),{x,0,30}],x] (* _Harvey P. Dale_, Jul 03 2013 *)

%Y Cf. A001622, A002420, A002421, A002422, A002423, A002424, A020923, A020925, A020927, A020929.

%K sign

%O 0,2

%A _N. J. A. Sloane_

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Last modified April 16 04:38 EDT 2024. Contains 371696 sequences. (Running on oeis4.)