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 A243465 Number of ways 3 domicules can be placed on an n X n square. 2
 0, 0, 0, 180, 4890, 36028, 154434, 488660, 1271450, 2883900, 5907298, 11182644, 19877850, 33562620, 54291010, 84691668, 128065754, 188492540, 270942690, 381399220, 526986138, 716104764, 958577730, 1265800660, 1650901530, 2128907708, 2716920674, 3434298420 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..1000 FORMULA G.f.: 2*x^3*(15*x^6-167*x^5+320*x^4+686*x^3-2789*x^2-1815*x-90)/(x-1)^7. a(n) = (2574-2328*n-144*n^5-96*n^4+1188*n^3-854*n^2+32*n^6)/3 for n>=3, a(n) = 0 for n<3. EXAMPLE a(3) = 180: +-----+ +-----+ +-----+ +-----+ |o-o | | o | | o | | o | | | | \ | | / | | / | |o-o | |o o o| |o o | |o o o| | | || | | | / | | X | | o-o| |o o | |o o-o| | o o| +-----+ +-----+ +-----+ +-----+ ... . MAPLE a:= n-> `if`(n<3, 0, ((((((32*n-144)*n-96)*n+1188)*n-854) *n-2328)*n+2574)/3): seq(a(n), n=0..50); CROSSREFS Column k=3 of A243424. Sequence in context: A008432 A289318 A250146 * A271673 A008378 A214818 Adjacent sequences: A243462 A243463 A243464 * A243466 A243467 A243468 KEYWORD nonn,easy AUTHOR Alois P. Heinz, Jun 05 2014 STATUS approved

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Last modified December 6 18:41 EST 2023. Contains 367614 sequences. (Running on oeis4.)