2,2

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

J. Goldman and G.-C. Rota, The number of subspaces of a vector space, pp. 75-83 of W. T. Tutte, editor, Recent Progress in Combinatorics. Academic Press, NY, 1969.

I. P. Goulden and D. M. Jackson, Combinatorial Enumeration. Wiley, NY, 1983, p, 99.

M. Sved, Gaussians and binomials, Ars. Combinatoria, 17A (1984), 325-351.

S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

S. Plouffe, 1031 Generating Functions and Conjectures, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

G.f.: 1/[(1-x)(1-5x)(1-25x)].

A006111:=-1/(z-1)/(25*z-1)/(5*z-1); [Conjectured by S. Plouffe in his 1992 dissertation.]

(Other) sage: [gaussian_binomial(n, 2, 5) for n in xrange(2, 16)] # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 28 2009]

Sequence in context: A166488 A051587 A069380 this_sequence A157878 A084330 A009975

Adjacent sequences: A006108 A006109 A006110 this_sequence A006112 A006113 A006114

nonn

N. J. A. Sloane (njas(AT)research.att.com).