%I #5 Jan 05 2023 11:05:05

%S 1,4,25,107,448,1701,6216,21771,74339,248379

%N Number of free holey polyiamonds of n cells with simply-connected interiors.

%F a(n) = A070764(n) - A359523(n).

%Y Cf. A000577, A070764, A359520, A359523.

%K nonn,more

%O 9,2

%A _John Mason_, Jan 05 2023