28006

Appears in sequences

• Number of ways to place 3 nonattacking bishops on a 3 X n board.at n=19A172207
• An oscillating sequence: a(n) = n^2 + 2^(n-1) - 2*a(n-1), n>0, with a(1) = 1.at n=15A238315
• G.f. satisfies: A(x) = Sum_{n>=0} (A(x)^n - 1)^n * x^n / (1-2*x)^(n+1).at n=7A251181
• G.f.: (1 + 5*x + 5*x^2 + x^3)/Product_{i=1..10} (1 - x^i).at n=29A256977
• The number of edges in a graph induced by a regular drawing of K_{n,n}.at n=17A290132
• Number T(n,k) of entries in the k-th cycles of all permutations of [n] when cycles are ordered by increasing lengths (and increasing smallest elements); triangle T(n,k), n>=1, 1<=k<=n, read by rows.at n=51A322383
• Number of entries in the seventh cycles of all permutations of [n] when cycles are ordered by increasing lengths.at n=3A332911