9,2

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.

Sequence in context: A103793 A064117 A015334 this_sequence A072922 A061127 A136295

Adjacent sequences: A015374 A015375 A015376 this_sequence A015378 A015379 A015380

sign,easy

Olivier Gerard (ogerard(AT)ext.jussieu.fr)