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 A271899 a(n) = 1 + 471*n/140 + 1594*n^2/315 + 73*n^3/16 + 161*n^4/60 + 83*n^5/80 + 61*n^6/240 + n^7/28 + 11*n^8/5040. 1
 1, 18, 162, 927, 3906, 13248, 38256, 97614, 225819, 482482, 965250, 1827189, 3299556, 5720976, 9574128, 15531132, 24508917, 37735938, 56831698, 83900619, 121641894, 173477040, 243696960, 337630410, 461835855, 624318786, 834776658, 1104873697, 1448547912, 1882352736, 2425835808 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Values of Ehrhart polynomial for a facet of the Birkhoff polytope B_4. LINKS Jesus A. De Loera, Fu Liu, and Ruriko Yoshida, A generating function for all semi-magic squares and the volume of the Birkhoff polytope, J. Algebraic Combin. 30 (2009), no. 1, 113-139. Index entries for linear recurrences with constant coefficients, signature (9,-36,84,-126,126,-84,36,-9,1). FORMULA a(n) = (n+4)*(n+3)*(n+2)*(n+1)*(11*n^4+70*n^3+196*n^2+269*n+210)/5040. G.f.: (1 + 9*x + 36*x^2 + 33*x^3 + 9*x^4)/(1 - x)^9. - Ilya Gutkovskiy, Apr 16 2016 MAPLE f:=n-> 1 + 471*n/140 + 1594*n^2/315 + 73*n^3/16 + 161*n^4/60 + 83*n^5/80 + 61*n^6/240 + n^7/28 + 11*n^8/5040; [seq(f(n), n=0..30)]; MATHEMATICA CoefficientList[Series[(1 + 9 x + 36 x^2 + 33 x^3 + 9 x^4)/(1 - x)^9, {x, 0, 30}], x] (* Michael De Vlieger, Apr 16 2016 *) PROG (Python) A271899_list, m = [], [88, -128, 61, -8]+[1]*5 for _ in range(100):     A271899_list.append(m[-1])     for i in range(8):         m[i+1] += m[i] # Chai Wah Wu, Apr 16 2016 (PARI) lista(nn) = for(n=0, nn, print1((1/5040)*(n+4)*(n+3)*(n+2)*(n+1)*(11*n^4+70*n^3+196*n^2+269*n+210), ", ")); \\ Altug Alkan, Apr 16 2016 CROSSREFS Sequence in context: A222914 A171642 A158808 * A128797 A008418 A099196 Adjacent sequences:  A271896 A271897 A271898 * A271900 A271901 A271902 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Apr 16 2016 STATUS approved

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Last modified April 24 22:26 EDT 2019. Contains 322446 sequences. (Running on oeis4.)