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 A064835 If n mod 2 = 0 then n^4/4-2*n^2+3*n else n^4/4-2*n^2+3*n-5/4. 2
 0, 0, 2, 10, 44, 120, 270, 522, 920, 1504, 2330, 3450, 4932, 6840, 9254, 12250, 15920, 20352, 25650, 31914, 39260, 47800, 57662, 68970, 81864, 96480, 112970, 131482, 152180, 175224, 200790, 229050, 260192, 294400, 331874, 372810 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Harry J. Smith, Table of n, a(n) for n = 0..1000 G. L. Cohen and E. Tonkes, Dartboard arrangements, Elect. J. Combin., 8 (No. 2, 2001), #R4. FORMULA G.f.: 2*x^2*(1+x+7*x^2-3*x^3)/((1-x)^5*(1+x)). [Colin Barker, Apr 20 2012] PROG (PARI) { for (n=0, 1000, a=n^4/4 - 2*n^2 + 3*n; if (n%2, a-=5/4); write("b064835.txt", n, " ", a) ) } [From Harry J. Smith, Sep 28 2009] CROSSREFS Sequence in context: A175613 A121949 A005144 * A225958 A025590 A122932 Adjacent sequences:  A064832 A064833 A064834 * A064836 A064837 A064838 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Oct 25 2001 STATUS approved

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