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A258717
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If n even then 2*n^2-4*n else 2*n^2-4*n-3.
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1
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0, 3, 16, 27, 48, 67, 96, 123, 160, 195, 240, 283, 336, 387, 448, 507, 576, 643, 720, 795, 880, 963, 1056, 1147, 1248, 1347, 1456, 1563, 1680, 1795, 1920, 2043, 2176, 2307, 2448, 2587, 2736, 2883, 3040, 3195, 3360, 3523, 3696, 3867, 4048, 4227, 4416, 4603, 4800, 4995, 5200, 5403, 5616, 5827
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OFFSET
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2,2
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REFERENCES
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J. A. Hendrickson, Jr., Submatrices of 0,1 matrices, Problem 1470, Math. Mag., 69 (No. 2, 1996), 146-148.
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LINKS
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FORMULA
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G.f.: x^3*(-3-10*x+5*x^2) / ( (1+x)*(x-1)^3 ). - R. J. Mathar, Jun 18 2015
a(n) = -a(n-1)-12*n+3+4*n^2, n>=3. - R. J. Mathar, Nov 07 2015
a(n) = 2*a(n-1)-2*a(n-3)+a(n-4) for n>5.
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MAPLE
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f:=n-> if (n mod 2)=0 then 2*n^2-4*n else 2*n^2-4*n-3; fi;
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PROG
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(PARI) concat(0, Vec(x^3*(5*x^2-10*x-3)/((x-1)^3*(x+1)) + O(x^50))) \\ Colin Barker, Apr 02 2016
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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