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A057617 Order of subgroup bP_{m+1} of group Theta_m of h-cobordism classes of smooth homotopy m-spheres defined by those homotopy m-spheres which bound parallelizable (m+1)-manifolds, where m = 2n+1. 2
1, 1, 1, 28, 2, 992, 1, 8128, 2, 130816 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
COMMENTS
a(1) = 1 because the Poincaré conjecture is true.
REFERENCES
M. A. Kervaire and J. W. Milnor, Groups of homotopy spheres: I. Ann. of Math. (2) 77 1963 504-537.
J. P. Levine, Lectures on groups of homotopy spheres. In Algebraic and geometric topology (New Brunswick, NJ, 1983), 62-95, Lecture Notes in Math., 1126, Springer, Berlin, 1985.
LINKS
John W. Milnor, Differential Topology Forty-six Years Later, Notices Amer. Math. Soc. 58 (2011), 804-809.
CROSSREFS
Cf. A001676.
Sequence in context: A358706 A040782 A040783 * A040771 A040770 A040772
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Feb 03 2002
EXTENSIONS
a(0)-a(1) from Andrey Zabolotskiy, Feb 02 2018
STATUS
approved

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Last modified March 29 03:51 EDT 2024. Contains 371264 sequences. (Running on oeis4.)