This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A270843 #35 Mar 28 2016 18:46:43 %S A270843 1,394,122601,8510140,210940745,2524556538,17167621086,72787256640, %T A270843 202996629360,382918536000,492133561920,424994169600,236107872000, %U A270843 76281004800,10897286400 %N A270843 Number of nonisomorphic edge colorings of the Petersen graph with exactly n colors. %C A270843 This is zero when n is more than fifteen because only fifteen edges are available. %C A270843 These are not colorings in the strict sense, since there is no requirement that adjacent edges have different colors. - _N. J. A. Sloane_, Mar 28 2016 %C A270843 The value for n=15 is 15!/120 because all orbits are the same size namely 120 (order of the symmetric group on five elements) when each of the 15 edges has a unique color. - _Marko Riedel_, Mar 28 2016 %H A270843 Math StackExchange, <a href="http://math.stackexchange.com/questions/1711016/">Edge colorings of the Petersen graph</a> %F A270843 Cycle index of the automorphisms acting on the edges is (1/120)*S[1]^15+(5/24)*S[2]^6*S[1]^3+(1/4)*S[4]^3*S[2]*S[1]+(1/6)*S[3]^5+(1/6)*S[3]*S[6]^2+(1/5)*S[5]^3. %F A270843 Inclusion-exclusion yields a(n) = sum(C(n, q)*(-1)^q*A270842(n - q), q = 0 .. n) %Y A270843 Cf. A270842, A063843. %K A270843 nonn,easy,fini,full %O A270843 1,2 %A A270843 _Marko Riedel_, Mar 24 2016