(For other notation see Notation for the Special Functions.)
|integers, nonnegative unless stated otherwise.|
|real or complex variables.|
|greatest common divisor of .|
|and relatively prime.|
Unless otherwise noted, the formulas in this chapter hold for all values of the variables and , and for all nonnegative integers .
The origin of the notation , , is not clear. The present notation, as defined in §24.2(i), was used in Lucas (1891) and Nörlund (1924), and has become the prevailing notation; see Table 24.2.1. Among various older notations, the most common one is
The secant series ((4.19.5)) first occurs in the work of Gregory in 1671. Its coefficients were first studied in Euler (1755); they were called Euler numbers by Raabe in 1851. The notations , , as defined in §24.2(ii), were used in Lucas (1891) and Nörlund (1924).