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a(n) is the number of n-celled fixed rounded polyominoes.
2

%I #7 Apr 12 2023 10:51:52

%S 1,4,20,113,682,4294,27830,184240,1239575,8446660,58150684,403735761

%N a(n) is the number of n-celled fixed rounded polyominoes.

%C See A056840 for the definition of rounded polyominoes.

%Y Cf. A056840, A362224.

%K nonn,more

%O 1,2

%A _John Mason_, Apr 11 2023