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: A038451 A068538 A112018 this_sequence A038131 A081734 A058362

Adjacent sequences: A015377 A015378 A015379 this_sequence A015381 A015382 A015383

sign,easy

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