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: A096561 A096560 A011581 this_sequence A016872 A016920 A017064

Adjacent sequences: A015380 A015381 A015382 this_sequence A015384 A015385 A015386

sign,easy

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