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 A087866 #15 Jul 23 2019 08:17:29
%S A087866 1,1,1,1,1,1,2,2,2,2,3,3,4,4,4,3,4,4,5,5,6,5,6,6,7,6,7,6,7,7,9,8,9,8,
%T A087866 9,8,10,9,10,9,11,10,12,11,12,10,12,11,13,12,14,12,14,13,15,13,15,13,
%U A087866 15,14,17,15,17,15,17,15,18,16,18,16,19,17,20,18,20,17,20,18,21,19,22,19
%N A087866 Composition length of the n-th symmetric power of the natural representation of a finite subgroup of SL(2,C) of type E_8 (binary icosahedral group).
%D A087866 Y. Ito, I. Nakamura, Hilbert schemes and simple singularities, New trends in algebraic geometry (Warwick, 1996), 151-233, Cambridge University Press, 1999.
%H A087866 <a href="/index/Rec#order_17">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,1,-1,0,0,1,-1,0,0,0,0,-1,1)
%F A087866 G.f.: (1-x^15)/((1-x)*(1-x^6)*(1-x^10)).
%F A087866 a(n) = n/60*(15+(-1)^n+b(n)) where b(n) is the 30-periodic sequence {60, 46, 28, 18, -4, -10, 24, 22, -8, -6, 20, 26, 48, 58, 16, -30, -16, 2, 12, 34, 40, 6, 8, 38, 36, 10, 4, -18, -28, 14}. - _Benoit Cloitre_, Oct 27 2003
%t A087866 CoefficientList[Series[(1-x^15)/((1-x)(1-x^6)(1-x^10)),{x,0,100}],x] (* _Harvey P. Dale_, Jan 20 2019 *)
%o A087866 (PARI) a(n)=polcoeff((1-x^15)/((1-x)*(1-x^6)*(1-x^10))+O(x^(n+1)),n)
%Y A087866 Cf. A008651.
%K A087866 easy,nonn
%O A087866 0,7
%A A087866 _Paul Boddington_, Oct 27 2003
%E A087866 More terms from _Benoit Cloitre_, Oct 27 2003