The operator representing the computation of a derivative,
(1)

sometimes also called the NewtonLeibniz operator. The second derivative is then denoted , the third , etc. The integral is denoted .
The differential operator satisfies the identity
(2)

where is a Hermite polynomial (Arfken 1985, p. 718), where the first few cases are given explicitly by
(3)
 
(4)
 
(5)
 
(6)
 
(7)
 
(8)

The symbol can be used to denote the operator
(9)

(Bailey 1935, p. 8). A fundamental identity for this operator is given by
(10)

where is a Stirling number of the second kind (Roman 1984, p. 144), giving
(11)
 
(12)
 
(13)
 
(14)

and so on (OEIS A008277). Special cases include
(15)
 
(16)
 
(17)

A shifted version of the identity is given by
(18)

(Roman 1984, p. 146).