2,2

a(n)= A091534(n, 3)/10, n>=2.

a(n)= product(3*j+2, j=0..n-1)*(product(3*(j+1), j=0..n-1) - 3*product(3*j+1, j=0..n-1))/(3!*10). From eq.(12) of the Blasiak et reference(see A091534) for r=5, s=2 and k=3.

a(n)= (3^(2*n))*risefac(2/3, n)*(n!-3*risefac(1/3, n))/(3!*10), with risefac(x, n)=pochhammer(x, n).

a(n)= (fac3(3*n-1)/10)*(fac3(3*n) - 3*fac3(3*n-2))/3!, with fac3(3*n) := A032031(n)= n!*3^n, fac3(3*n-1) := A008544(n) and fac3(3*n-2)=A007559(n) (triple factorials: fac3(n)=A007661(n)).

E.g.f.: (hypergeom([2/3, 1], [], 9*x)-3*hypergeom([1/3, 2/3], [], 9*x)+2)/(3!*10).

Cf. A091540.

Sequence in context: A164759 A015272 A048920 this_sequence A157874 A069172 A104437

Adjacent sequences: A091536 A091537 A091538 this_sequence A091540 A091541 A091542

nonn,easy

Wolfdieter Lang (wolfdieter.lang_AT_physik_DOT_uni-karlsruhe_DOT_de), Feb 13 2004