%I #4 Mar 30 2012 17:26:08
%S 1,6,240,448,138240,225280,402554880,1857945600,1010722406400,
%T 301234913280,5859811786752,55010477998080,9141306387333120000,
%U 7898088718655815680,1017975879293416243200,161212016644168089600
%N Denominators of coefficients of series expansion of a certain integral in the theory of charged particle beams.
%C The integral is Integrate[1/Sqrt[Log[y]],{y,1,x}]=Sqrt[Pi]*Erfi[Sqrt[Log[x]] with series expansion Sqrt[x-1]*Sum[c(i)*(x-1)^(i-1),{i,0,19}]. Numerator(c(n))= A077230(n), denominator(c(n))=A077231(n).
%D M. Reiser, Theory and design of charged particle beams. J. Wiley, N.Y. 1994, S. Humphries, Charged particle beams. J. Wiley, N.Y. 1990.
%e Series expansion is Sqrt[x-1]*(2 + 1/6 (x-1) -7/240 (x-1)^2+ 5/448 (x-1)^3 -...), hence a(0)=1, a(1)=6, a(2)=240, a(3)=448, etc.
%Y Cf. A077230.
%K frac,nonn
%O 0,2
%A _Zak Seidov_, Oct 31 2002