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Number of n-member subsets of [9*n] whose elements sum to a multiple of nine.
2

%I #4 Aug 29 2018 17:18:59

%S 1,1,17,327,6545,135751,2869719,61474519,1329890705,28987537806,

%T 635627275767,14005614014756,309847743790935,6878045467021470,

%U 153121753939078375,3417374882384868702,76435265515004093841,1712879663609111933495,38450113512250685307822

%N Number of n-member subsets of [9*n] whose elements sum to a multiple of nine.

%H Alois P. Heinz, <a href="/A318597/b318597.txt">Table of n, a(n) for n = 0..735</a>

%e a(2) = 17: {1,8}, {1,17}, {2,7}, {2,16}, {3,6}, {3,15}, {4,5}, {4,14}, {5,13}, {6,12}, {7,11}, {8,10}, {9,18}, {10,17}, {11,16}, {12,15}, {13,14}.

%Y Column k=9 of A318557.

%K nonn

%O 0,3

%A _Alois P. Heinz_, Aug 29 2018