276318

Appears in sequences

• Number of 4-block ordered bicoverings of an unlabeled n-set.at n=29A060091
• a(n) = 972*n^2 - 270*n (n>=1).at n=16A305071
• T(n,k) is the number of permutations of the multiset {1, 1, 2, 2, ..., n, n} with k occurrences of fixed pairs (j,j), where T(n,k), n >= 2, 0 <= k <= n-2 is a triangle read by rows.at n=33A375220