2,2

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.

G.f.: 1/[(1-x)(1+11x)(1-121x)].

Sequence in context: A098034 A109242 A078270 this_sequence A103849 A010032 A129947

Adjacent sequences: A015259 A015260 A015261 this_sequence A015263 A015264 A015265

nonn,easy

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