11,2

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: A076254 A015432 A034618 this_sequence A018869 A017088 A017172

Adjacent sequences: A015415 A015416 A015417 this_sequence A015419 A015420 A015421

sign,easy

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