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 A270842 #43 Dec 24 2017 08:58:11 %S A270842 1,396,123786,9002912,254721400,3920311044,39571426713,293231076608, %T A270842 1715840171595,8333541708700,34810892718492,128392921513440, %U A270842 426551317876970,1296405100924948,3649123762524675,9607693522053120,23853550135649477,56222046462953772 %N A270842 Number of nonisomorphic edge colorings of the Petersen graph with at most n colors. %C A270842 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 %H A270842 Colin Barker, <a href="/A270842/b270842.txt">Table of n, a(n) for n = 1..1000</a> %H A270842 Math StackExchange, <a href="http://math.stackexchange.com/questions/1711016/">Edge colorings of the Petersen graph</a> %F A270842 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 A270842 a(n) = n^15/120 + 5*n^9/24 + 5*n^5/12 + 11*n^3/30. %F A270842 G.f.: x*(1 + 380*x + 117570*x^2 + 7069296*x^3 + 125309188*x^4 + 856514276*x^5 + 2594956089*x^6 + 3729352800*x^7 + 2594956089*x^8 + 856514276*x^9 + 125309188*x^10 + 7069296*x^11 + 117570*x^12 + 380*x^13 + x^14) / (1 - x)^16. - _Colin Barker_, Dec 24 2017 %o A270842 (PARI) a(n) = n^15/120 + 5*n^9/24 + 5*n^5/12 + 11*n^3/30; \\ _Altug Alkan_, Mar 25 2016 %Y A270842 Cf. A270843, A063843. See A159233 for edge colorings where adjacent edges must have different colors. %K A270842 nonn,easy %O A270842 1,2 %A A270842 _Marko Riedel_, Mar 24 2016