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: A015272 A015273 A015274 this_sequence A015276 A015277 A015278

Sequence in context: A092715 A036517 A063935 this_sequence A051306 A004225 A004226

sign,easy

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