9,2

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: A130430 A130428 A022251 this_sequence A027570 A154532 A157745

Adjacent sequences: A015382 A015383 A015384 this_sequence A015386 A015387 A015388

sign,easy

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