%I #30 Jul 19 2022 05:49:49
%S 1,1,3,8,25,85,397,2183,15129,122585
%N Numbers of terms in expressions for coefficients of "Lovelock Lagrangians" (or "Gauss-Bonnet forms") in terms of Riemann-Christoffel curvature tensor and two of its contractions (viz., the Ricci curvature tensor and the Riemann curvature scalar) for n-dimensional differentiable manifolds having a general linear connection.
%H C. Bogdanos, <a href="https://doi.org/10.1103/PhysRevD.79.107501">Diagrammatic derivation of Lovelock densities</a>, Phys Rev. D 79 (10) (2009) 107501.
%H C. C. Briggs, <a href="http://arXiv.org/abs/gr-qc/9607033">A General Expression for the Quintic Lovelock Tensor</a>, arXiv:gr-qc/9607033, 1996-1997.
%H C. C. Briggs, <a href="http://arXiv.org/abs/gr-qc/9703074">A General Expression for the Quartic Lovelock Tensor</a>, arXiv:gr-qc/9703074, 1997.
%H R. J. Mathar, <a href="https://arxiv.org/abs/1903.12477">2-regular digraphs of the Lovelock Lagrangian</a>, arXiv:1903.12477 [math.GM], 2019.
%Y Cf. A006373, A045900 (conjectural), A306892 (2-regular digraphs).
%K nonn,more
%O 0,3
%A C. C. Briggs (ccb104(AT)vm.cac.psu.edu)
%E a(6)-a(8) from _R. J. Mathar_, Apr 08 2019
%E a(9) added by _R. J. Mathar_, Apr 15 2019