CasimirOperatorAS

Let $A_0, A_1,\cdots,A_d$ be adjacency matrices of an association scheme R. Let a be an element of the adjacency algebra of R over the complex number field. CasimirOperatorAS(a, R) returns

$$\sum_{i=0}^d \frac{1}{n_i}A_i a A_{i^*}.$$

It is known that this element is in the center of the adjacency algebra.