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: A015269 A015270 A015271 this_sequence A015273 A015274 A015275

Sequence in context: A007267 A035811 A004393 this_sequence A048920 A091539 A069172

sign,easy

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