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A327470
Maximum valency of the central line in a certain smooth 2D-polarized K3-surface in P^{n+1}.
0
12, 9, 8, 7, 6, 5, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4
OFFSET
2,1
LINKS
Alex Degtyarev, Lines on smooth polarized K3-surfaces, arXiv:1706.05734 [math.AG], 2017; Discrete & Computational Geometry 62.3 (2019): 601-648, DOI:10.1007/s00454-018-0038-5. Prop. 2.10.
PROG
(Python)
def a(n): return 4 if n > 11 else 5 if n > 6 else 12-n if n > 2 else 12
print([a(n) for n in range(2, 50)]) # Michael S. Branicky, Dec 09 2021
CROSSREFS
Sequence in context: A326927 A338289 A018870 * A068614 A163920 A038335
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Oct 03 2019
EXTENSIONS
a(8)-a(11) edited to match Proposition 2.12, p. 11, of Degtyarev link. - Michael S. Branicky, Dec 09 2021
STATUS
approved