                /**  Euler numbers and polynomials  **/
 
/*A: S.Wolfram */
/*S: California Institute of Technology */
/*D: February 1982 */
 
/* Explicit forms for integer values of index. */
 
Eul[$n_=Oddp[$n]] : 0
 
Eul[$n_=Evenp[$n]] : 2^$n Eul[$n,1/2]
 
Eul[$n_=Natp[1+$n],$x] : 2^($n+1)/($n+1) (Ber[$n+1,($x+1)/2] - \
                                Ber[$n+1,$x/2])
/*R: AS 23.1.10 */

