12,2

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: A015426 A015427 A015428 this_sequence A015430 A015431 A015432

Sequence in context: A090874 A071371 A052094 this_sequence A103752 A105383 A034252

nonn,easy

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