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 A054620 Number of ways to color vertices of a pentagon using <= n colors, allowing only rotations. 4
 0, 1, 8, 51, 208, 629, 1560, 3367, 6560, 11817, 20008, 32219, 49776, 74269, 107576, 151887, 209728, 283985, 377928, 495235, 640016, 816837, 1030744, 1287287, 1592544, 1953145, 2376296, 2869803, 3442096, 4102253, 4860024 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..10000 Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1). FORMULA a(n) = (n^5+4*n)/5 = n*(n^2-2*n+2)*(n^2+2*n+2)/5. G.f.: x*(1+2*x+18*x^2+2*x^3+x^4) / (x-1)^6 . - R. J. Mathar, Aug 30 2011 a(n) = -a(-n). - Bruno Berselli, Aug 31 2011 PROG (MAGMA) [(n^5+4*n)/5: n in [0..40]]; // Vincenzo Librandi, Aug 31 2011 CROSSREFS Cf. A060446, A006527, A006528, A006565, A054621, ..., A075195. Sequence in context: A215874 A078304 A000851 * A034516 A240360 A069325 Adjacent sequences:  A054617 A054618 A054619 * A054621 A054622 A054623 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Apr 16 2000 STATUS approved

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Last modified August 1 01:56 EDT 2021. Contains 346377 sequences. (Running on oeis4.)