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 A229598 Voids left when packing boomerangs into n X n coins. 10
 1, 0, 3, 8, 5, 12, 21, 16, 27, 40, 33, 48, 65, 56, 75, 96, 85, 108, 133, 120, 147, 176, 161, 192, 225, 208, 243, 280, 261, 300, 341, 320, 363, 408, 385, 432, 481, 456, 507, 560, 533, 588, 645, 616, 675, 736, 705, 768 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,3 COMMENTS The inverse patterns are voids or stars (consist of 4 perimeter parts of coins) appearing in n X n coins using the same rule as A229593. LINKS Kival Ngaokrajang, Illustration of initial terms FORMULA Empirical g.f.: -x^2*(x+1)*(x^4-2*x^3+5*x^2-2*x+1) / ((x-1)^3*(x^2+x+1)^2). - Colin Barker, Oct 06 2013 EXAMPLE For n = 2, there is no boomerang can be packed into 2X2 coins, there is 1 void left, a(2) = 1. For n = 3, there are 2 boomerangs can be packed into 3X3 coins with no void left, a(3) = 0. ... PROG (Small Basic) v=1 d=-1 d=3 d=5 For n=2 To 100   If n+1 >=6 Then     If Math.Remainder(n+1, 3)=0 Then       d[n+1]=d[n-2]-2     Else       d[n+1]=d[n-2]+4     EndIf   EndIf   v[n+1]=v[n]+d[n+1]   TextWindow.Write(v[n]+", ") EndFor CROSSREFS Cf. A229093 (Illustration of inverse clubs patterns). Sequence in context: A323707 A291186 A058055 * A078356 A050093 A120072 Adjacent sequences:  A229595 A229596 A229597 * A229599 A229600 A229601 KEYWORD nonn AUTHOR Kival Ngaokrajang, Sep 26 2013 STATUS approved

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Last modified July 14 16:05 EDT 2020. Contains 335729 sequences. (Running on oeis4.)