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%I #6 Feb 08 2013 18:22:32
%S 1,2,4,8
%N Dimensions of finite-dimensional real division algebras.
%C In 1958 Michel Kervaire and John Milnor independently proved that any finite-dimensional real division algebra must be of dimension 1, 2, 4, or 8.
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Division_algebra">Division algebra</a>
%F a(n) = 2^n = A222010(n) + 1 for n = 0, 1, 2, 3.
%e The real, complex, quaternion, and Cayley numbers are real division algebras of dimensions 1, 2, 4, 8, respectively, so those are members.
%Y Cf. A222010.
%K nonn,fini,full
%O 0,2
%A _Jonathan Sondow_, Feb 06 2013