…
►In a symbol, if the three angular momenta do not satisfy the triangle conditions (34.2.1), or if the projective quantum numbers do not satisfy (34.2.3), then the symbol is zero.
…However, the and symbols may vanish for certain combinations of the angular momenta and projective quantum numbers even when the triangle conditions are fulfilled.
…
…
►They therefore satisfy the triangle conditions
…The corresponding projective quantum numbers
are given by
…
►►►Figure 34.2.1: Angular momenta and projective quantum numbers
, .
Magnify►If either of the conditions (34.2.1) or (34.2.3) is not satisfied, then the symbol is zero.
When both conditions are satisfied the symbol can be expressed as the finite sum
…
…
►
…
►Then the number of plane partitions in is
…
►The number of symmetric plane partitions in is
…
►The example of a strict shifted plane partition also satisfies the conditions of a descending plane partition.
The number of descending plane partitions in is
…
►For the Bernoulli numbers
, see §24.2(i).
►With the same conditions,
…For explicit formulas for in terms of Stirling numbers see Nemes (2013a), and for asymptotic expansions of as see Boyd (1994) and Nemes (2015a).
…
►Next, and again with the same conditions,
…
…
►Sufficient conditions for the validity of this second result are:
…
►First, the conditions can be weakened.
…For example, Condition (b) can be replaced by:
…
►Furthermore, (2.10.31) remains valid with the weaker condition
…
►In Condition (c) we have
…