7,2

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: A017707 A013970 A036100 this_sequence A019288 A105649 A015337

Adjacent sequences: A015346 A015347 A015348 this_sequence A015350 A015351 A015352

sign,easy

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