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).

A130813

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).

Terms

    a(0) =128a(1) =1024a(2) =4608a(3) =15360a(4) =42240a(5) =101376a(6) =219648a(7) =439296a(8) =823680a(9) =1464320a(10) =2489344a(11) =4073472a(12) =6449664a(13) =9922560a(14) =14883840a(15) =21829632a(16) =31380096a(17) =44301312a(18) =61529600a(19) =84198400a(20) =113667840a(21) =151557120a(22) =199779840a(23) =260582400a(24) =336585600a(25) =430829568a(26) =546822144a(27) =688590848a(28) =860738560

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