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%I #25 Dec 20 2021 02:01:23
%S 1,1,1,1,5,3,1,45,29,6,807,422,46,20022,8270,424,642162,211848
%N Number of ways of placing maximum number of nonattacking rooks on a triangular board with edge-length n (symmetric solutions count only once).
%C The rooks placements are considered different when they cannot be obtained by a rotation and/or reflection of another solution that leaves the board inchanged. - _Alain Brobecker_, Dec 19 2021
%C a(n) = A350191(n) for n <> 10,13,16,19,... - _Vaclav Kotesovec_, Dec 20 2021
%H Alain Brobecker, <a href="http://abrobecker.free.fr/text/NonAttackingRooks.pdf">Non Attacking Rooks on Hexhex and Triangular boards</a>
%Y Cf. A004396, A289893, A350191.
%K nonn,more,hard
%O 1,5
%A _Alain Brobecker_, Dec 10 2021
%E a(17)-a(18) from _Vaclav Kotesovec_, Dec 19 2021