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 3-subsets of X containing none of X_i, (i=1,...,n).

A130809

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 3-subsets of X containing none of X_i, (i=1,...,n).

Terms

    a(0) =8a(1) =32a(2) =80a(3) =160a(4) =280a(5) =448a(6) =672a(7) =960a(8) =1320a(9) =1760a(10) =2288a(11) =2912a(12) =3640a(13) =4480a(14) =5440a(15) =6528a(16) =7752a(17) =9120a(18) =10640a(19) =12320a(20) =14168a(21) =16192a(22) =18400a(23) =20800a(24) =23400a(25) =26208a(26) =29232a(27) =32480a(28) =35960a(29) =39680

External references