A094155 Bisection of A000939.

2, 14, 332, 18264, 1664354, 222406776, 40865005494, 9880209206458, 3041127561315224, 1161157777643184900, 538583682082245127336, 298292500833816420226008, 194444097328912809590995986, 147362699895662080130636012160, 128481853971530055408959624233748, 127695847335468919414701788927638656

Offset: 2

Author

N. J. A. Sloane, May 05 2004

Keywords

• nonn

Links

• S. W. Golomb and L. R. Welch, On the enumeration of polygons, Amer. Math. Monthly, 67 (1960), 349-353.

Programs

Maple

with(numtheory); f:=proc(n) local t1,d; t1:=2^(n/2)*(n/2)*(n/2)!; for d from 1 to n do if n mod d = 0 then t1:=t1+phi(n/d)^2*d!*(n/d)^d; fi; od: t1/(2*n^2); end;

Formula

See Maple line.