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A172229 Number of ways to place 3 nonattacking wazirs on a 3 X n board. 6
0, 2, 22, 84, 215, 442, 792, 1292, 1969, 2850, 3962, 5332, 6987, 8954, 11260, 13932, 16997, 20482, 24414, 28820, 33727, 39162, 45152, 51724, 58905, 66722, 75202, 84372, 94259, 104890, 116292, 128492, 141517, 155394, 170150, 185812, 202407, 219962, 238504 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Wazir is a (fairy chess) leaper [0,1].

LINKS

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

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

Eric Weisstein's World of Mathematics, Grid Graph

Wikipedia, Wazir (chess)

FORMULA

a(n) = (3*n - 5)*(3*n^2 - 8*n + 8)/2, n>=2.

G.f.: x^2*(3*x^3+8*x^2+14*x+2)/(x-1)^4. - Vaclav Kotesovec, Mar 25 2010

MATHEMATICA

CoefficientList[Series[x (3 x^3 + 8 x^2 + 14 x + 2) / (x - 1)^4, {x, 0, 50}], x] (* Vincenzo Librandi, May 28 2013 *)

CROSSREFS

Cf. A172226, A061989.

Sequence in context: A123061 A050853 A291915 * A212894 A281647 A281140

Adjacent sequences:  A172226 A172227 A172228 * A172230 A172231 A172232

KEYWORD

nonn,easy

AUTHOR

Vaclav Kotesovec, Jan 29 2010

EXTENSIONS

More term from Vincenzo Librandi, May 28 2013

STATUS

approved

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Last modified December 18 21:01 EST 2018. Contains 318245 sequences. (Running on oeis4.)