Error in integration (10637)

[Alberto Candel]

My Prime (also 10637) returns 2 values, one exact and one approximate, and a warning that says that the Prime cannot verify that they are the same.

The exact is (1/3) [Gamma(1/3,-216)-Gamma(1/3)]
and the approximate is 5.96393809188E91,

There is no documentation entry for the Gamma(x,y) function that I can find.