5,2

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: A041843 A041840 A012793 this_sequence A101732 A006301 A004704

Adjacent sequences: A015302 A015303 A015304 this_sequence A015306 A015307 A015308

sign,easy

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