%I #7 Aug 03 2021 19:01:31
%S 1,3,9,41,231,1551,12037,105861,1039539,11268059,133585089,1718984673,
%T 23857531519,355190381031,5646040979901,95432906354621,
%U 1709068974897867,32325104169244851,643869687410800249,13471540400560532889,295384662114697463319
%N a(2)=1; for n>2, a(n) = A109742(n)/3.
%Y Cf. A000166, A109742.
%K nonn
%O 2,2
%A _N. J. A. Sloane_, Aug 13 2005