%I #12 Apr 15 2023 14:34:50
%S 0,0,1,3,7,23,73,261,916,3370,12418,46527,174991,663380,2524605,
%T 9652679,37028654,142514143,550002180,2128047718,8252388728,
%U 32068797010,124855150040,486952692675,1902227344361,7441861777311,29153922116412,114358089656116
%N Increase in the number of free polyominoes from order n to n+1.
%H John Mason, <a href="/A283109/b283109.txt">Table of n, a(n) for n = 0..49</a>
%F a(n) = A000105(n+1) - A000105(n).
%Y Cf. A000105.
%K nonn
%O 0,4
%A _Francois Alcover_, Feb 28 2017