History of $\hat A$-genus polynomials $\hat A_n(p_1,\dots,p_n)$

 Title: $\hat A$-genus polynomials $\hat A_n(p_1,\dots,p_n)$ Definition: The entry is the homogeneous component $\hat A_n(p_1,\dots,p_n)$ of the-  $\hat A$-class of a real vector bundle $E$, written as a polynomial in the Pontryagin-  classes $p_i$ CITE{PontryaginWiki}. It is defined by the characteristic power series-  $Q(x)=\frac{\sqrt{x}/2}{\sinh(\sqrt{x}/2)}$ through Formula CITE{formula-component}.+  $\hat A$-class of a real vector bundle $E$, written in the Pontryagin classes $p_i$+  CITE{PontryaginWiki} and defined by Formulas CITE{formula-component} and CITE{formula-series}. Parameters:   n: