The confluent hypergeometric function is defined as
Φ(a;b;z)=(Γ(b))/(Γ(a)Γ(b-a)) ∫_0^1〖e^zt t^(a-1) 〖(1-t)〗^(b-a-1) dt,0
Sources:
NIST SP 800-22 Rev. 1a