Equations (24.5.3) and (24.5.4) enable
and
to be computed by recurrence. For higher values
of
more efficient methods are available. For example, the tangent numbers
can be generated by simple recurrence relations obtained from
(24.15.3), then (24.15.4) is applied. A similar method
can be used for the Euler numbers based on (4.19.5). For details see
Knuth and Buckholtz (1967).
Another method is based on the identities
If
denotes the right-hand side of (24.19.1) but
with the second product taken only for
,
then
for
. For proofs and
further information see Fillebrown (1992).
For number-theoretic applications it is important to compute
for
; in particular to find the
irregular pairs
for which
.
We list here three methods, arranged in increasing order of efficiency.
Tanner and Wagstaff (1987) derives a congruence
for Bernoulli
numbers in terms of sums of powers. See also §24.10(iii).
Buhler et al. (1992) uses the expansion
and computes inverses modulo
of the left-hand side. Multisectioning
techniques are applied in implementations. See also
Crandall (1996, pp. 116–120).