%I #21 Mar 28 2023 14:01:26
%S 1,2,18,134,1010,7788,60978,482708,3853338,30964238,250150176,
%T 2029781310,16530857930,135051216620,1106287906140,9083459084364,
%U 74734798117570,615998603183550,5085522355488150,42045309424052250,348067638153560040,2884832348569699340
%N Expansion of 1/sqrt(1 - 4*x/(1-x)^6).
%F a(n) = Sum_{k=0..n} binomial(2*k,k) * binomial(n+5*k-1,n-k).
%F n*a(n) = (11*n-9)*a(n-1) - (25*n-60)*a(n-2) + 35*(n-3)*a(n-3) - 35*(n-4)*a(n-4) + 21*(n-5)*a(n-5) - 7*(n-6)*a(n-6) + (n-7)*a(n-7) for n > 6.
%F a(0) = 1; a(n) = (2/n) * Sum_{k=0..n-1} (n+k) * binomial(n+4-k,5) * a(k).
%o (PARI) my(N=30, x='x+O('x^N)); Vec(1/sqrt(1-4*x/(1-x)^6))
%Y Cf. A085362, A110170, A162478, A359489, A359758.
%K nonn
%O 0,2
%A _Seiichi Manyama_, Mar 24 2023