%I A108694
%S A108694 1,1,2,3,9,6,13,54,69,26,75,399,747,573,150,541,3508,8638,9998,5393,
%T A108694 1082,4683,35817,109248,169038,139143,57585,9366,47293,416762,1515531,
%U A108694 2935222,3256907,2064534,691645,94586
%N A108694 Triangle T(n,k), 0<=k<=n, read by rows, given by [1, 2, 2, 4, 3, 6, 4, 
               8, 5, 10, 6, 12, . . . ] DELTA [2, 1, 4, 2, 6, 3, 8, 4, 10, 5, 12, 
               6, . . . ] where DELTA is the operator defined in A084938.
%C A108694 Related to preferential arrangements of n elements (A000670) and necklaces 
               of sets of labeled beads (A000629).
%F A108694 Sum_{ k>=0 } T(n, k) = n!*3^n = A032031(n).
%F A108694 T(n, 0) = A000670(n); T(n, n) = A000629(n).
%e A108694 1; 1, 2; 3, 9, 6; 13, 54, 69, 26; 75, 399, 747, 573, 150; ...
%Y A108694 Cf. A000629, A000670, A032031, A084938.
%Y A108694 Sequence in context: A011164 A082234 A011028 this_sequence A016634 A021421 
               A152812
%Y A108694 Adjacent sequences: A108691 A108692 A108693 this_sequence A108695 A108696 
               A108697
%K A108694 easy,nonn,tabl
%O A108694 0,3
%A A108694 Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jun 18 2005