151557120

Appears in sequences

• If X_1,...,X_n is a partition of a 2n-set X into 2-blocks then a(n) is equal to the number of 7-subsets of X containing none of X_i, (i=1,...n).at n=21A130813
• a(n) = 2^n * binomial(4*n,n).at n=7A386918