19404000

Appears in sequences

• T(n,k) = Sum of multinomial(n; n_1,n_2,...,n_k)^2, where the sum extends over all compositions (n_1,n_2,...,n_k) of n into exactly k nonnegative parts.at n=25A192722
• a(n) = A025487(n) * A324576(n) = A025487(n) * A276086(A025487(n)).at n=25A324577
• Triangular array read by rows. T(n,k) is the number of ways to form an ordered pair of n-permutations and then choose a size k subset of its common descent set, n >= 0, 0 <= k <= max{0,n-1}.at n=24A362589