1,2

Also sixth column (m=5) sequence of triangle A091543.

P. Blasiak, K. A. Penson and A. I. Solomon, The general boson normal ordering problem, Phys. Lett. A 309 (2003) 198-205.

a(n)= product((5*j+2)*(5*j+1), j=0..n-1)/2, n>=1. From eq.12 of the Blasiak et al. reference with r=7, s=2, k=1.

a(n)= (5^(2*n))*risefac(1/5, n)*risefac(2/5, n)/2, n>=1, with risefac(x, n) = Pochhammer(x, n).

a(n)= fac5(5*n-3)*fac5(5*n-4)/2, n>=1, with fac5(5*n-4)/2 = A034323(n), and fac5(5*n-3)= A008548(n) (5-factorials).

E.g.f.: (hypergeom([1/5, 2/5], [], 25*x)-1)/2.

a(n)=A091747(n, 2), n>=1.

Sequence in context: A053875 A048538 A102967 this_sequence A101630 A005791 A006699

Adjacent sequences: A091542 A091543 A091544 this_sequence A091546 A091547 A091548

nonn,easy

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