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.

Adjacent sequences: A015344 A015345 A015346 this_sequence A015348 A015349 A015350

Sequence in context: A043650 A137819 A115495 this_sequence A064820 A032595 A032596

sign,easy

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