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A104996 Numerators of coefficients in a series solution to a certain differential equation. 3

%I #22 May 20 2023 23:16:55

%S 1,-3,-5,-193,-13397,-315629,-282682949,-71668311457,-24436072994261,

%T -829687356768133,-5984214162917084933,-4076572731127688098561,

%U -669050282555409820416913,-3254803666762108782733299553,-3704926048371364507765541554757,-975581171350361622823383714646061

%N Numerators of coefficients in a series solution to a certain differential equation.

%C Serial solution of o.d.e. (A. Gruzinov, 2005): cos(t)*f'(t) + sin(t)*f''(t) + (3/4)*sin(t)*f(t) = 0, f(-Pi/2) = 1, f'(-Pi/2) = 0, f(t) = 1 - (3/8)*(t + Pi/2)^2 - (5/128)*(t + Pi/2)^4 - (193/15360)*(t + Pi/2)^4 - ... All coefficients (except for 1) are negative, and there is no simple recursion or other formula for the serial coefficients.

%H Andrei Gruzinov, <a href="https://doi.org/10.1103/PhysRevLett.94.021101">Power of an axisymmetric pulsar</a>, Physical Review Letters, Vol. 94, No. 2 (2005), 021101; <a href="https://arxiv.org/abs/astro-ph/0407279">arXiv preprint</a>, arXiv:astro-ph/0407279, 2004.

%t CoefficientList[Series[Hypergeometric2F1[-1/4, 3/4, 1/2, Sin[x]^2], {x, 0, 30}], x][[1 ;; -1 ;; 2]] // Numerator (* _Amiram Eldar_, Apr 29 2023 *)

%Y Cf. A104997 (denominators).

%K sign,frac

%O 1,2

%A _Zak Seidov_, Mar 31 2005

%E More terms from _Amiram Eldar_, Apr 29 2023

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Last modified March 28 10:55 EDT 2024. Contains 371241 sequences. (Running on oeis4.)