A174642 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A174642

Number of ways to place 4 nonattacking amazons (superqueens) on a 4 X n board.

0, 0, 0, 0, 0, 0, 0, 12, 60, 180, 432, 900, 1692, 2940, 4800, 7452, 11100, 15972, 22320, 30420, 40572, 53100, 68352, 86700, 108540, 134292, 164400, 199332, 239580, 285660, 338112, 397500, 464412, 539460, 623280, 716532, 819900, 934092, 1059840

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,8

COMMENTS

An amazon (superqueen) moves like a queen and a knight

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

The Oprisch Family Web Site

V. Kotesovec, Number of ways of placing non-attacking queens and kings on boards of various sizes

FORMULA

G.f.: -12*x^8*(x^3+1)/(x-1)^5.

Explicit formula: a(n) = (n-7)(n^3-21n^2+158n-420), n>=7.