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: A103576 A125574 A052097 this_sequence A011575 A059277 A010813

Adjacent sequences: A015351 A015352 A015353 this_sequence A015355 A015356 A015357

sign,easy

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