A094154 Bisection of A000939.

1, 4, 54, 2246, 164950, 18423144, 2905943328, 615376173184, 168483518571798, 57926238289970076, 24434798429947993054, 12408968034664788792008, 7468360391233437715595634, 5256695596753687250025931048, 4278271932454694494134007741950, 3986830862631720154048770746485900

Offset

1,2

Links

Table of n, a(n) for n=1..16.

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

Formula

See Maple line.

Maple

with(numtheory); f:=proc(n) local t1, d; t1:=0; 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;

Crossrefs

Cf. A000939, A094155.

Sequence in context: A355128 A355126 A357511 * A168510 A324235 A125531

Adjacent sequences: A094151 A094152 A094153 * A094155 A094156 A094157

Keyword

nonn

Author

N. J. A. Sloane, May 05 2004

Status

approved