11,2

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: A017361 A017481 A017613 this_sequence A130681 A028520 A017084

Adjacent sequences: A015406 A015407 A015408 this_sequence A015410 A015411 A015412

sign,easy

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