%I
%S 1,2,5,15,47,145,470
%N Arises in counting relative Milnor rings in Ktheory.
%C Column 3 of Marshall table, p. 443. A143093 is the analogous enumeration, column 2 of Marshall table, if we view the Kstructures as graded rings with distinguished element.
%D Ido Efrat, Valuations, orderings and Milnor Ktheory, Mathematical Surveys and Monographs, vol. 124, American Mathematical Society, 2006.
%D Murray Marshall, Book Review: Valuations, orderings and Milnor Ktheory, by Ido Efrat, Bulletin of the American Mathematical Society, Vol. 45 (July 2008) No. 3, pp. 439444.
%F a(n) = the number of nonisomorphic elementary types K_*(F)/S with F^X/S = 2^n, if we view the Kstructures just as graded rings.
%Y Cf. A143093.
%K more,nonn
%O 0,2
%A _Jonathan Vos Post_, Jul 23 2008
