Can someone tell the me the data bank which has all the STO-3G basis sets for many electron atoms? I am trying to express the slater orbitals of Helium atom in terms of 3 gaussian functions (STO-3G basis set). Is there any data bank or reference table in which I can find the exponents and coefficients in it ? 
Also in primitive cartesian gaussian , it seems like both $2s$ and $2p$ has the same functional form. For $2p$ it is $x\exp(-\alpha x^{2})$ , $y\exp(-\alpha y^{2})$ and $z\exp(-\alpha z^{2})$. What is for  $2s$ orbital in primitive gaussian function ?
A wide range of Gaussian basis sets for all elements can be found at the Basis Set Exchange. Alternatively, you can try to extract that data from the basis set library of a quantum chemistry software package.
The functional form of a primitive cartesian gaussian with $l=0$ is $\exp(-\alpha r^2)$, independent of the $n$ quantum number.