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: A078143 A106787 A105012 this_sequence A105175 A069376 A066703

Adjacent sequences: A015347 A015348 A015349 this_sequence A015351 A015352 A015353

sign,easy

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