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Number of self-conjugate set partitions of {1, ..., n}.
7

%I #5 Feb 14 2019 20:22:12

%S 1,1,0,1,1,2,7,7,46,39,321

%N Number of self-conjugate set partitions of {1, ..., n}.

%C This sequence counts set partitions fixed under Callan's conjugation operation.

%H David Callan, <a href="https://arxiv.org/abs/math/0508052">On conjugates for set partitions and integer compositions</a>, arXiv:math/0508052 [math.CO], 2005.

%e The a(3) = 1 through a(7) = 7 self-conjugate set partitions:

%e {{12}{3}} {{13}{24}} {{123}{4}{5}} {{135}{246}} {{13}{246}{57}}

%e {{13}{2}{45}} {{124}{35}{6}} {{15}{246}{37}}

%e {{13}{25}{46}} {{1234}{5}{6}{7}}

%e {{14}{2}{356}} {{124}{3}{56}{7}}

%e {{14}{236}{5}} {{134}{2}{5}{67}}

%e {{14}{25}{36}} {{14}{2}{3}{567}}

%e {{145}{26}{3}} {{14}{23}{57}{6}}

%Y Cf. A000110, A000126, A000296, A001610, A032032, A052841, A080107, A169985, A306416, A324011, A324012.

%K nonn,more

%O 0,6

%A _Gus Wiseman_, Feb 14 2019