OFFSET
1,2
FORMULA
Equals sqrt(2)*arcsinh(1) - 4*log(2) + (sqrt(2)-1)*Pi/2 - gamma, where gamma is Euler's constant (A001620). - Amiram Eldar, Jun 03 2022
EXAMPLE
psi(5/8) = -1.45270876457656...
MATHEMATICA
RealDigits[PolyGamma[5/8], 10, 100][[1]] (* Amiram Eldar, Jun 03 2022 *)
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
R. J. Mathar, Jun 01 2022
STATUS
approved