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 A159191 Number of n-colorings of the Robertson graph. 2
 0, 0, 0, 24, 3490848, 3501104400, 564523119840, 31643453033640, 886834653776064, 15220684846368288, 181298924180884800, 1627952400490177080, 11672280987833510880, 69664869701930893104, 357038627052783076128, 1609181428647593728200, 6498071673405936462720 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS The Robertson graph is the unique (4,5) cage: the quartic graph on 19 vertices (so 38 edges) with girth 5. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..1000 Weisstein, Eric W. "Robertson Graph". Weisstein, Eric W. "Chromatic Polynomial". Timme, Marc; van Bussel, Frank; Fliegner, Denny; Stolzenberg, Sebastian (2009) "Counting complex disordered states by efficient pattern matching: chromatic polynomials and Potts partition functions", New J. Phys. 11 023001, doi: 10.1088/1367-2630/11/2/023001. FORMULA a(n) = n^19 -38*n^18 + ... (see Maple program). MAPLE a:= n-> n^19 -38*n^18 +703*n^17 -8436*n^16 +73761*n^15 -500004*n^14 +2727105*n^13 -12246808*n^12 +45913333*n^11 -144701057*n^10 +383839223*n^9 -853388854*n^8 +1574465385*n^7 -2370057775*n^6 +2835163369*n^5 -2587310804*n^4 +1685281636*n^3 -693467820*n^2 +134217080*n: seq(a(n), n=0..20); CROSSREFS The adjacency lists of the Robertson graph are included in A184945. Cf. A115400, A140986, A157959, A157991, A157992, A157993, A158343, A158344, A158346, A158347, A158348, A158760, A158792, A158904, A159042, A159055, A159056, A159192, A159299, A166964, A173705, A173710. Sequence in context: A319977 A268505 A172734 * A013820 A294326 A255322 Adjacent sequences:  A159188 A159189 A159190 * A159192 A159193 A159194 KEYWORD nonn AUTHOR Alois P. Heinz, Apr 05 2009 STATUS approved

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Last modified October 17 15:32 EDT 2019. Contains 328116 sequences. (Running on oeis4.)