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Total number of triangles in all polyiamonds with n triangles.
1

%I #6 Aug 01 2020 17:37:36

%S 1,2,3,12,20,72,168,528,1440,4480,13046,40008,120055,366324,1109745,

%T 3380752,10269819,31253904,95011267,288979680,878550498,2671223720,

%U 8120041693,24682865208,75020015675,227999634772,692872971246,2105464666676

%N Total number of triangles in all polyiamonds with n triangles.

%H S. T. Coffin, <a href="https://johnrausch.com/PuzzlingWorld/chap02.htm#fig024">The Puzzling World of Polyhedral Dissections</a>, Chap 2, Table 1.

%Y a(n) = n*A000577(n).

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Aug 04 2004