A194497 Number of ways to arrange 7 nonattacking queens on the lower triangle of an n X n board.

0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 1210, 27198, 322782, 2564988, 15372702, 74615814, 306900410, 1105651074, 3569169990, 10512880400, 28628691842, 72880455042, 174895586328, 398556484840, 867314768878, 1811576604968, 3646385889888

Offset

1,10

Comments

Column 7 of A194498.

Links

R. H. Hardin, Table of n, a(n) for n = 1..28

Example

Some solutions for 10 X 10:
  0                    0                    0
  0 0                  0 0                  0 0
  0 0 0                0 0 0                0 0 0
  0 1 0 0              0 1 0 0              0 0 0 1
  0 0 0 1 0            0 0 0 1 0            1 0 0 0 0
  1 0 0 0 0 0          0 0 0 0 0 1          0 0 1 0 0 0
  0 0 0 0 0 0 1        1 0 0 0 0 0 0        0 0 0 0 0 1 0
  0 0 0 0 1 0 0 0      0 0 1 0 0 0 0 0      0 1 0 0 0 0 0 0
  0 0 1 0 0 0 0 0 0    0 0 0 0 1 0 0 0 0    0 0 0 0 0 0 1 0 0
  0 0 0 0 0 1 0 0 0 0  0 0 0 0 0 0 1 0 0 0  0 0 0 0 1 0 0 0 0 0

Crossrefs

Sequence in context: A233252 A249849 A027879 * A287226 A015108 A070065

Adjacent sequences: A194494 A194495 A194496 * A194498 A194499 A194500

Keyword

nonn

Author

R. H. Hardin, Aug 26 2011

Status

approved