A301894 Number of real lines on a smooth real cubic surface.
3, 7, 15, 27
Offset: 1
Examples
The number of lines on a smooth complex cubic surface is a(4) = A027363(2) = A238370(1) = 27.
Links
- D. Schläfli, On the distribution of surfaces of the third order into species, in reference to the absence or presence of singular points, and the reality of their lines, Philosophical Transactions of the Royal Society of London, 153 (1863), 193-241.
- Kirsten Wickelgren, An Arithmetic Count of the Lines on a Smooth Cubic Surface, AMS Notices, 65 (2018), 404-405.
Formula
a(n) = A097080(n) = 2*n^2 - 2*n + 3 for n = 1, 2, 3, 4.
Comments