OFFSET
0,2
FORMULA
a(n)= product(5*j+2, j=0..n-1)*(-3*product(5*j+1, j=0..n-1) + product(5*j+3, j=0..n-1))/(3!*14), n>=2. From eq.12 of the Blasiak et al. reference given in A007840 with r=7, s=2, k=3.
a(n)= (5^(2*n))*risefac(2/5, n)*(-3*risefac(1/5, n) + risefac(3/5, n))/(3!*14), n>=2, with risefac(x, n)=Pochhammer(x, n).
E.g.f.: (hypergeom([2/5, 3/5], [], 25*x) - 3*hypergeom([1/5, 2/5], [], 25*x) + 2)/(3!*14).
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Feb 13 2004
STATUS
approved