1022320

Appears in sequences

• Number of ways to place n nonattacking bishops on an n X n board.at n=7A002465
• Number of quasi-initially connected digraphs with n labeled nodes.at n=4A049414
• E.g.f. exp(2x)/(1-3x).at n=6A097817
• Number of ways to place 7 nonattacking bishops on an n X n board.at n=6A187239
• Triangle read by rows: T(n, k) = n! * 3^k * hypergeom([-k], [-n], 2/3).at n=27A375600
• Total number of ways to place k nonattacking bishops on an n X n chess board. Triangle T(n,k) read by rows (0 <= k <= 2*n-[n>0]-[n>1]).at n=45A378590