3,2

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: A015274 A015275 A015276 this_sequence A015278 A015279 A015280

Sequence in context: A060520 A065759 A088894 this_sequence A135418 A034818 A068260

sign,easy

Olivier Gerard (olivier.gerard(AT)gmail.com)